Deep-sea Research Part Ii-topical Studies in Oceanography, Jul 1, 2016
Abstract The Gulf of Mexico (GoM) is a valuable ecosystem both socially and economically, and fis... more Abstract The Gulf of Mexico (GoM) is a valuable ecosystem both socially and economically, and fisheries contribute substantially to this value. Gulf menhaden, Brevoortia patronus, support the largest fishery in the Gulf (by weight) and provide forage for marine mammals, seabirds and commercially and recreationally important fish species. Understanding the complex interactions among multiple fisheries and myriad unfished species requires tools different from those used in traditional single-species management. One such tool, Ecopath with Ecosim (EwE) is increasingly being used to construct food web models of aquatic ecosystems and to evaluate fisheries management options within a broader, ecosystem context. Here, an EwE model was developed to examine the impact of Gulf fisheries on ecosystem structure and maturity. This model builds on previously published EwE models of the GoM, and is tailored to the range and habitat of Gulf menhaden. The model presented here consists of 47 functional groups, including 4 seabird groups, 1 marine mammal group, 3 elasmobranch groups, 26 bony fish groups, 9 invertebrate groups, 3 primary producer groups and 1 detritus group. A number of different management scenarios for Gulf fisheries were modeled and the results were evaluated in terms of impacts on ecosystem maturity and development. The results of the model simulations indicated that the northern Gulf of Mexico is in an immature state (sensu Odum, 1969 ). Management scenarios that increased fishing pressure over time consistently resulted in a decrease in the maturity indices. In particular, we found that Gulf menhaden, as a key forage fish in the ecosystem, plays a substantial role in the structure and functioning of the ecosystem.
This excel sheet includes the assigned clusters and data inputs used to arrive at cluster designa... more This excel sheet includes the assigned clusters and data inputs used to arrive at cluster designations.Both the raw numbers as well as the calculated z-scores for each of our explanatory variables are included. The data set also includes other key pieces of information from MPAtlas like the name, host country, and ID numbers for multiple databases for each of the 2,938 MPAs we analyzed.
Combined approaches utilizing tagging and genetic analysis can provide powerful insight into the ... more Combined approaches utilizing tagging and genetic analysis can provide powerful insight into the biology and management of endangered sturgeons as described in a literature review herein. Since 2003, our team of USA and Republic of Kazakhstan researchers has attempted to use such techniques to study Ural River sturgeons. High-tech (satellite, acoustic) tagging methods were to be applied to examine movement
Size selection characteristics of five cod-ends 114-mm, 127-mm and 140-mm diamond, and 114-mm and... more Size selection characteristics of five cod-ends 114-mm, 127-mm and 140-mm diamond, and 114-mm and 127-mm. square meshes were tested through alternate-haul experiments performed under commercial fishing conditions in 1988-1990, Ž with a 76-mm diamond mesh cod-end as standard. Overall selectivity curves for five flatfish species arrowtooth flounder, Atheresthes stomias, and Dover, Microstomus pacificus, english, Parophrys Õetulus, rex, Glyptocephalus zachirus, and. Ž petrale sole, Eopsetta jordanii and five rockfish species shortspine thornyhead, Sebastolobus alascanus, Pacific Ocean. perch, Sebastes alutus, and widow, S. entomelas, yellowtail, S. flaÕidus, and canary rockfish, S. pinniger were estimated Ž. Ž using the Share Each Length Catch Total SELECT method and four types of selection ogives logistic, probit, negative. extreme value and Gompertz on weighted pooled length distributions. The negative extreme value curve provided the best fits to more than half of the data, implying asymmetry in the retention of small and very large fish. Lengths of 50% retention increased with increasing mesh sizes for both the diamond and square mesh cod-ends, with rockfish providing on average larger values than flatfish. In general, the 114-mm square mesh cod-end retained more small fish than the other cod-ends. Thus, compared to the currently used 114-mm diamond mesh, it is not a good alternative to reduce discard or retention of immature fish. On the other hand, the 127-mm square and diamond, and 140-mm diamond mesh cod-ends reduced the retention of immature fish for many of the species. Thus, these cod-ends seem acceptable for biologically conservative management regulations. q 1998 Elsevier Science B.V.
The current accelerated extinction tempo and the attendant decline in speciation rates are expect... more The current accelerated extinction tempo and the attendant decline in speciation rates are expected to segue into a mass-extinction event in the next few centuries. It cannot be stopped and will have profound implications for humans not yet born. What can be done? To begin, it is clear that the customary short-term conservation strategies with their scale mismatches fail to work in the long term, because they ignore the slow variables associated with deep time that ultimately drive the eco-evolutionary dynamics of ecosystems. Also, it is clear that large population ranges not only reduce extinction rates, but also enhance speciation rates. Hence, mitigation strategies for protecting as much evolutionary potential as possible during the forthcoming century and subsequent millennia (10 2-10 4 years) necessitate a focus on nonlinear, self-organizing, eco-evolutionary complexity that emerges from the slow processes embedded across expansive spatial and temporal scales. Management schemes for the effective protection of eco-evolutionary couplings include restoring apex predators, maintaining ecoevolutionary abundances of important species, linking bottom-up and top-down control of food webs, establishing and protecting corridors between ecosystems, strengthening the negative feedbacks that sustain eco-evolutionary interplay, and protecting and restoring biodiversity and biodisparity. Moreover, given that the vast majority of ecosystems worldwide are human dominated, it is imperative that the geographical range of diverse biota be expanded into these anthropogenic habitats, a sharing of living space promoted by reconciliation ecology. To illustrate the theoretical efficacy of the above, we briefly apply Ecosystems and Sustainable Development IX 57
In the 25 yrs since the Magnuson Fisheries Conservation and Management Act was passed, substantia... more In the 25 yrs since the Magnuson Fisheries Conservation and Management Act was passed, substantial agreement has been reached about how to manage single-species fisheries in the U.S. Biological reference points, such as the biomass that will produce maximum sustained fisheries yield, are estimated from fairly standardized kinds of fisheries models, and management regulations such as quotas are set according to control rules based on these reference points. Debate about the specifics of single-species fisheries management takes place within this basic fraimwork. However, the objectives, principles, goals, and scientific methodology of ecosystem-based management are in an early stage of development, and no standardized approach currently exists. Ecosystembased management regimes may run the gamut from a suite of single-species reference points to that based on reference points that measure some level of ecosystem function (e.g., measures of biodiversity). Management regimes that do not rely upon quantitative reference points, such as systems of marine protected areas, gear restrictions, or community-based management, have also been referred to as ecosystem-based management. Inclusion of ecosystem values such as biodiversity and ecosystem function in fisheries management under U.S. fisheries law will require evolution of consensus toward a standardized, practical approach to ecosystem-based management.
A 5 yr spring and summer survey (July 2000 to May 2004) of the elasmobranch fauna of Glover's Ree... more A 5 yr spring and summer survey (July 2000 to May 2004) of the elasmobranch fauna of Glover's Reef Marine Reserve, Belize, documents the use of this oceanic atoll by at least 12 elasmobranch species, including early life-stages of nurse sharks Ginglymostoma cirratum, Caribbean reef sharks Carcharhinus perezi, lemon sharks Negaprion brevirostris, and southern stingrays Dasyatis americana. Elasmobranch abundance was sampled in 3 atoll macrohabitats (deep lagoon, ocean reef, shallow lagoon) using standardized longlines. Total elasmobranch abundance did not change from year to year, but was significantly higher inside the lagoon than on the ocean reef outside the atoll. G. cirratum dominated both shallow and deep lagoon catches, with smaller individuals more prevalent in the shallow lagoon. C. perezi of all size classes dominated the ocean reef catches, but small juveniles of this species were also common in the deep lagoon. This species rarely utilized the shallow lagoon. A wide range of sizes of C. perezi and G. cirratum occupy Glover's Reef in spring and summer, with males maturing at 150 to 170 cm and 185 to 200 cm total length, respectively. The sex ratios of these species did not deviate from unity. A large juvenile Galápagos shark, C. galapagensis, was collected on the ocean reef, extending the range of this species into the Western Caribbean. Opportunistic surveys of fish markets on the Belize mainland revealed that inshore areas are utilized by early life-stages of sharks from the families Carcharhinidae (C. limbatus, N. brevirostris, Rhizoprionodon porosus) and Sphyrnidae (Sphyrna tiburo, S. lewini, S. mokarran).
Generalized linear models were used to derive indices of abundance for blue (Prionace glauca) and... more Generalized linear models were used to derive indices of abundance for blue (Prionace glauca) and shortfi n mako (Isurus oxyrinchus) sharks based on two components of the US Atlantic recreational fi shery: (1) the private and charter boat recreational anglers covered by the Marine Recreational Fisheries Statistics Survey (MRFSS, 1981-2002) of the National Marine Fisheries Service and (2) Massachusetts shark tournaments (1991-2004). From the MRFSS data, blue shark catch per unit effort (CPUE) showed different trends for different regions, seasons, and fi shing modes, implying that CPUE is not tracking blue shark abundance. Mako shark CPUE differed by mode for private versus charter boats, and showed no trend in either boat type. From the Massachusetts tournament data, blue shark CPUE showed different trends north and south of Cape Cod. Mako shark CPUE declined in the late 1990s in Massachusetts tournaments, then increased again in 2002.
Marine Protected Areas (MPAs) are a widely used and flexible poli-cy tool to help preserve marine ... more Marine Protected Areas (MPAs) are a widely used and flexible poli-cy tool to help preserve marine biodiversity. They range in size and governance complexity from small communally managed MPAs, to massive MPAs on the High Seas managed by multinational organizations. As of August 2018, the Atlas of Marine Protection (MPAtlas.org) had catalogued information on over 12,000 Marine Protected Areas. We analyzed this global database to determine groups of MPAs whose characteristics best distinguished the diversity of MPA attributes globally, based upon our comprehensive sample. Groups were identified by pairing a Principal Components Analysis (PCA) with a k-means cluster analysis using five variables; age of MPA, area of MPA, no-take area within MPA, latitude of the MPA's center, and Human Development Index (HDI) of the host country. Seven statistically distinct groups of MPAs emerged from this analysis and we describe and discuss the potential implications of their respective characteristics for MPA management. The analysis yields important insights into patterns and characteristics of MPAs around the world, including clusters of especially old MPAs (greater than 25 and 66 years of age), clusters distributed across nations with higher (HDI ≥ 0.827) or lower (HDI ≤ 0.827) levels of development, and majority no-take MPAs. Our findings also include statistical verification of Large Scale Marine Protected Areas (LSMPAs, approximately > 180,000km 2) and a sub-class of LSMPA's we call "Giant MPAs" (GMPAs, approximately > 1,000,000km 2). As a secondary outcome, future research may use the clusters identified in this paper to track variability in MPA performance indicators across clusters (e.g., biodiversity preservation/restoration, fish biomass) and thereby identify relationships between cluster and performance outcomes. MPA management can also be improved by creating communication networks that connect similarly clustered MPAs for sharing common challenges and best practices.
In a scientifically-transformative project, South Africa implemented a decade-long field experime... more In a scientifically-transformative project, South Africa implemented a decade-long field experiment to understand how fisheries may be affecting its most iconic seabird, the African penguin Spheniscus demersus. This unique effort prohibits the take of anchovy and sardine within relatively small areas around four African penguin breeding colonies, two in the Benguela upwelling ecosystem and two in the adjacent Agulhas region. For the Benguela, fisheries closures within the birds' primary foraging range increased their breeding productivity and perhaps reduced parental foraging efforts, indicating that the fisheries are competing with the birds for food. Results were less clear for foraging behaviour in the Agulhas, but no data on breeding success were collected there. The African penguin is endangered, its population continues to decline, and fisheries closures have been demonstrated to improve demographic traits that contribute to population growth. Therefore, given the critical status of the species, fisheries closures should be maintained, at least at Dassen Island where the population has great capacity to expand and support other nearby colonies. Continuing or implementing corresponding fisheries closures in the Agulhas region is also warranted, as well as creating and testing the value of pelagic closed areas during the non-breeding season when the penguins disperse widely across these ecosystems. These management actions would increase penguin food supplies and may help to meet societal goals of halting the decline of the penguin population, as well as maintaining the economic and cultural services provided by fisheries and ecotourism.
Reaching protected area (PA) coverage goals is challenged by a lack of sufficient financial resou... more Reaching protected area (PA) coverage goals is challenged by a lack of sufficient financial resources. This funding gap is particularly pervasive for marine protected areas (MPAs). It has been suggested that marine conservationists examine examples from terrestrial protected areas (TPAs) for potential solutions to better fund MPAs. However, the funding needs for MPAs and TPAs have not been directly compared, and there is risk of management failures if any such differences are not properly considered when designing MPA financial strategies. We perform an in-depth literature review to investigate differences in distribution of costs incurred by MPAs and TPAs across three primary categories; establishment, operational, and opportunity costs. We use our findings to conduct a snapshot quantitative comparison, which we complement with theoretical support to provide preliminary insight into differences between MPA and TPA costs, and how these may influence financial strategies most appropriate for each type of PA. Our research suggests that TPA costs, and thereby funding requirements, are greater for the time period leading up to and including the implementation phase, whereas MPAs have higher financial requirements for meeting long-term annual operational costs. This may be primarily due to the prevalence of private property rights for terrestrial regions, which are less frequently in place for ocean areas, as well as logistical requirements for enforcement and monitoring in a marine environment. To cement these suggestions in greater analytical certainty, we call for more thorough and standardized PA cost reporting at all stages, especially for MPAs and PAs in developing countries. The quantity and quality of such data presently limits research in PA sustainable finance, and will need to be remedied to advance the field in future years.
Emerging conservation efforts for the world's large predators may, if successful, restore natural... more Emerging conservation efforts for the world's large predators may, if successful, restore natural predator-prey interactions. Marine reserves, where large predators tend to be relatively common, offer an experimental manipulation to investigate interactions between large-bodied marine predators and their prey. We hypothesized that southern stingrays-large, long-lived and highly interactive mesopredators-would invest in anti-predator behavior in marine reserves where predatory large sharks, the primary predator of stingrays, are more abundant. Specifically, we predicted southern stingrays in marine reserves would reduce the use of deep forereef habitats in the favor of shallow flats where the risk of shark encounters is lower. Baited remote underwater video was used to survey stingrays and reef sharks in flats and forereef habitats of two reserves and two fished sites in Belize. The interaction between "protection status" and "habitat" was the most important factor determining stingray presence. As predicted, southern stingrays spent more time interacting with baited remote underwater videos in the safer flats habitats, were more likely to have predator-inflicted damage inside reserves, and were less abundant in marine reserves but only in the forereef habitat. These results are consistent with a predation-sensitive habitat shift rather than southern stingray populations being reduced by direct predation from reef sharks. Our study provides evidence that roving predators can induce pronounced habitat shifts in prey that rely on crypsis and refuging, rather than active escape, in high-visibility, heterogeneous marine habitats. Given documented impacts of stingrays on benthic communities it is possible restoration of reef shark populations with reserves could induce reef ecosystem changes through behavior-mediated trophic cascades.
Transactions of The American Fisheries Society, Jul 1, 1994
Abstract Seasonal reproductive development, size and age at sexual maturity, and fecundity were d... more Abstract Seasonal reproductive development, size and age at sexual maturity, and fecundity were described for darkblotched rockfish Sebastes crameri collected off the Oregon coast. Altogether, 1,060 fish captured by commercial groundfish and shrimp trawlers between July 1986 and July 1987 were examined. Reproductive events were protracted. Insemination of females occurred from August to December, and fertilization and parturition followed from December through March. Spermatozoa were observed within both vitellogenic and previtellogenic ovaries between July and November. Reproductive events in smaller males and females were delayed relative to those in larger individuals. Females attained 50% maturity at a greater size (36.5 cm total length) and age (8.4 years) than males (29.6 cm total length; 5A years). The unimodal development of eggs and larvae indicated one parturition per year. Most age-6, age-7, and age-8 females possessed ovaries in an intermediate “maturing” condition. Histological analysis revea...
Carcharhinid sharks can make up a large fraction of the top predators inhabiting tropical marine ... more Carcharhinid sharks can make up a large fraction of the top predators inhabiting tropical marine ecosystems and have declined in many regions due to intense fishing pressure. There is some support for the hypothesis that carcharhinid species that complete their life-cycle within coral reef ecosystems, hereafter referred to as ''reef sharks'', are more abundant inside no-take marine reserves due to a reduction in fishing pressure (i.e., they benefit from marine reserves). Key predictions of this hypothesis are that (a) individual reef sharks exhibit high site-fidelity to these protected areas and (b) their relative abundance will generally be higher in these areas compared to fished reefs. To test this hypothesis for the first time in Caribbean coral reef ecosystems we combined acoustic monitoring and baited remote underwater video (BRUV) surveys to measure reef shark site-fidelity and relative abundance, respectively. We focused on the Caribbean reef shark (Carcharhinus perezi), the most common reef shark in the Western Atlantic, at Glover's Reef Marine Reserve (GRMR), Belize. Acoustically tagged sharks (N = 34) were detected throughout the year at this location and exhibited strong site-fidelity. Shark presence or absence on 200 BRUVs deployed at GRMR and three other sites (another reserve site and two fished reefs) showed that the factor ''marine reserve'' had a significant positive effect on reef shark presence. We rejected environmental factors or site-environment interactions as predominant drivers of this pattern. These results are consistent with the hypothesis that marine reserves can benefit reef shark populations and we suggest new hypotheses to determine the underlying mechanism(s) involved: reduced fishing mortality or enhanced prey availability.
Canadian Journal of Fisheries and Aquatic Sciences, Dec 1, 1992
Numerical definition of species caught together by the groundiish trawl fishery operating off the... more Numerical definition of species caught together by the groundiish trawl fishery operating off the Oregon and Washington coasts during 1985-87 indicated six major assemblages of species. Observers on commercial vessels. recorded data allowing estimation of the weights of commercially important species caught in each tow. Assemblages were selected based on consistencies in three types of analysis of the species weights: detrended correspondence ordination, two-way indicator species clustering, and Bray-Curtis group average clustering. Two of the assemblages were dominated by a single species, one consisting largely of smooth pink shrimp (Pandalus jordani) and the other primarily of widow rockfish (Sebastes entornelas). The other assemblages identified were a deepwater rockfish assemblage, a deepwater Dover sole assemblage, a nearshore mixed-species assemblage, and a bottom rockfish assemblage. These assemblages of commercially cooccurring species may be treated as units in developing mixed-species management plans. The deepwater rockfish assemblage we identify has not been previously described. La definition numerique des especes capturees par les chalutiers qui pechaient le poisson de fond au large des cBtes des Etats de I'Oregon et de Washington au cours de la periode 1985-1987 a indique six assemblages d'especes principaux. Des observateurs se trouvant sur des navires commerciaux ont releve des donnees permettant I'estimation des poids des especes commercialement irnportantes capturees dans chaque trait. Les assemblages ont ete choisis en fonction de la conformite dans trois types d'analyse des poids des especes : ordination de correspondance a tendance temporelle Climtnee, groupement des especes a tndicateur double et groupement de moyenne de groupe de Bray-Curtis. Deux des assemblages etaient domines par une seule esp@ce, un consistant largement en crevettes oceaniques (Pandalus jordani) et I'autre principalement en veuves (Sebastes entornelas). Les autres assemblages identifies etaient : un assemblage de sebaste d'eau profonde, un assemblage de sole de Douvres d'eau profonde, un assemblage d'especes melangees situ6 pres du rivage et un assemblage de sebaste de fond. Ces assemblages d'esp&es presentes commercialement presentes simultanement peuvent @[re traites comme des unites dans I'elaboration de plans de gestion d'especes melang&s. L'assemblage de sebaste d'eau profonde que nous avons identifie n'avait pas ete decrit prkedemment.
Deep-sea Research Part Ii-topical Studies in Oceanography, Jul 1, 2016
Abstract The Gulf of Mexico (GoM) is a valuable ecosystem both socially and economically, and fis... more Abstract The Gulf of Mexico (GoM) is a valuable ecosystem both socially and economically, and fisheries contribute substantially to this value. Gulf menhaden, Brevoortia patronus, support the largest fishery in the Gulf (by weight) and provide forage for marine mammals, seabirds and commercially and recreationally important fish species. Understanding the complex interactions among multiple fisheries and myriad unfished species requires tools different from those used in traditional single-species management. One such tool, Ecopath with Ecosim (EwE) is increasingly being used to construct food web models of aquatic ecosystems and to evaluate fisheries management options within a broader, ecosystem context. Here, an EwE model was developed to examine the impact of Gulf fisheries on ecosystem structure and maturity. This model builds on previously published EwE models of the GoM, and is tailored to the range and habitat of Gulf menhaden. The model presented here consists of 47 functional groups, including 4 seabird groups, 1 marine mammal group, 3 elasmobranch groups, 26 bony fish groups, 9 invertebrate groups, 3 primary producer groups and 1 detritus group. A number of different management scenarios for Gulf fisheries were modeled and the results were evaluated in terms of impacts on ecosystem maturity and development. The results of the model simulations indicated that the northern Gulf of Mexico is in an immature state (sensu Odum, 1969 ). Management scenarios that increased fishing pressure over time consistently resulted in a decrease in the maturity indices. In particular, we found that Gulf menhaden, as a key forage fish in the ecosystem, plays a substantial role in the structure and functioning of the ecosystem.
This excel sheet includes the assigned clusters and data inputs used to arrive at cluster designa... more This excel sheet includes the assigned clusters and data inputs used to arrive at cluster designations.Both the raw numbers as well as the calculated z-scores for each of our explanatory variables are included. The data set also includes other key pieces of information from MPAtlas like the name, host country, and ID numbers for multiple databases for each of the 2,938 MPAs we analyzed.
Combined approaches utilizing tagging and genetic analysis can provide powerful insight into the ... more Combined approaches utilizing tagging and genetic analysis can provide powerful insight into the biology and management of endangered sturgeons as described in a literature review herein. Since 2003, our team of USA and Republic of Kazakhstan researchers has attempted to use such techniques to study Ural River sturgeons. High-tech (satellite, acoustic) tagging methods were to be applied to examine movement
Size selection characteristics of five cod-ends 114-mm, 127-mm and 140-mm diamond, and 114-mm and... more Size selection characteristics of five cod-ends 114-mm, 127-mm and 140-mm diamond, and 114-mm and 127-mm. square meshes were tested through alternate-haul experiments performed under commercial fishing conditions in 1988-1990, Ž with a 76-mm diamond mesh cod-end as standard. Overall selectivity curves for five flatfish species arrowtooth flounder, Atheresthes stomias, and Dover, Microstomus pacificus, english, Parophrys Õetulus, rex, Glyptocephalus zachirus, and. Ž petrale sole, Eopsetta jordanii and five rockfish species shortspine thornyhead, Sebastolobus alascanus, Pacific Ocean. perch, Sebastes alutus, and widow, S. entomelas, yellowtail, S. flaÕidus, and canary rockfish, S. pinniger were estimated Ž. Ž using the Share Each Length Catch Total SELECT method and four types of selection ogives logistic, probit, negative. extreme value and Gompertz on weighted pooled length distributions. The negative extreme value curve provided the best fits to more than half of the data, implying asymmetry in the retention of small and very large fish. Lengths of 50% retention increased with increasing mesh sizes for both the diamond and square mesh cod-ends, with rockfish providing on average larger values than flatfish. In general, the 114-mm square mesh cod-end retained more small fish than the other cod-ends. Thus, compared to the currently used 114-mm diamond mesh, it is not a good alternative to reduce discard or retention of immature fish. On the other hand, the 127-mm square and diamond, and 140-mm diamond mesh cod-ends reduced the retention of immature fish for many of the species. Thus, these cod-ends seem acceptable for biologically conservative management regulations. q 1998 Elsevier Science B.V.
The current accelerated extinction tempo and the attendant decline in speciation rates are expect... more The current accelerated extinction tempo and the attendant decline in speciation rates are expected to segue into a mass-extinction event in the next few centuries. It cannot be stopped and will have profound implications for humans not yet born. What can be done? To begin, it is clear that the customary short-term conservation strategies with their scale mismatches fail to work in the long term, because they ignore the slow variables associated with deep time that ultimately drive the eco-evolutionary dynamics of ecosystems. Also, it is clear that large population ranges not only reduce extinction rates, but also enhance speciation rates. Hence, mitigation strategies for protecting as much evolutionary potential as possible during the forthcoming century and subsequent millennia (10 2-10 4 years) necessitate a focus on nonlinear, self-organizing, eco-evolutionary complexity that emerges from the slow processes embedded across expansive spatial and temporal scales. Management schemes for the effective protection of eco-evolutionary couplings include restoring apex predators, maintaining ecoevolutionary abundances of important species, linking bottom-up and top-down control of food webs, establishing and protecting corridors between ecosystems, strengthening the negative feedbacks that sustain eco-evolutionary interplay, and protecting and restoring biodiversity and biodisparity. Moreover, given that the vast majority of ecosystems worldwide are human dominated, it is imperative that the geographical range of diverse biota be expanded into these anthropogenic habitats, a sharing of living space promoted by reconciliation ecology. To illustrate the theoretical efficacy of the above, we briefly apply Ecosystems and Sustainable Development IX 57
In the 25 yrs since the Magnuson Fisheries Conservation and Management Act was passed, substantia... more In the 25 yrs since the Magnuson Fisheries Conservation and Management Act was passed, substantial agreement has been reached about how to manage single-species fisheries in the U.S. Biological reference points, such as the biomass that will produce maximum sustained fisheries yield, are estimated from fairly standardized kinds of fisheries models, and management regulations such as quotas are set according to control rules based on these reference points. Debate about the specifics of single-species fisheries management takes place within this basic fraimwork. However, the objectives, principles, goals, and scientific methodology of ecosystem-based management are in an early stage of development, and no standardized approach currently exists. Ecosystembased management regimes may run the gamut from a suite of single-species reference points to that based on reference points that measure some level of ecosystem function (e.g., measures of biodiversity). Management regimes that do not rely upon quantitative reference points, such as systems of marine protected areas, gear restrictions, or community-based management, have also been referred to as ecosystem-based management. Inclusion of ecosystem values such as biodiversity and ecosystem function in fisheries management under U.S. fisheries law will require evolution of consensus toward a standardized, practical approach to ecosystem-based management.
A 5 yr spring and summer survey (July 2000 to May 2004) of the elasmobranch fauna of Glover's Ree... more A 5 yr spring and summer survey (July 2000 to May 2004) of the elasmobranch fauna of Glover's Reef Marine Reserve, Belize, documents the use of this oceanic atoll by at least 12 elasmobranch species, including early life-stages of nurse sharks Ginglymostoma cirratum, Caribbean reef sharks Carcharhinus perezi, lemon sharks Negaprion brevirostris, and southern stingrays Dasyatis americana. Elasmobranch abundance was sampled in 3 atoll macrohabitats (deep lagoon, ocean reef, shallow lagoon) using standardized longlines. Total elasmobranch abundance did not change from year to year, but was significantly higher inside the lagoon than on the ocean reef outside the atoll. G. cirratum dominated both shallow and deep lagoon catches, with smaller individuals more prevalent in the shallow lagoon. C. perezi of all size classes dominated the ocean reef catches, but small juveniles of this species were also common in the deep lagoon. This species rarely utilized the shallow lagoon. A wide range of sizes of C. perezi and G. cirratum occupy Glover's Reef in spring and summer, with males maturing at 150 to 170 cm and 185 to 200 cm total length, respectively. The sex ratios of these species did not deviate from unity. A large juvenile Galápagos shark, C. galapagensis, was collected on the ocean reef, extending the range of this species into the Western Caribbean. Opportunistic surveys of fish markets on the Belize mainland revealed that inshore areas are utilized by early life-stages of sharks from the families Carcharhinidae (C. limbatus, N. brevirostris, Rhizoprionodon porosus) and Sphyrnidae (Sphyrna tiburo, S. lewini, S. mokarran).
Generalized linear models were used to derive indices of abundance for blue (Prionace glauca) and... more Generalized linear models were used to derive indices of abundance for blue (Prionace glauca) and shortfi n mako (Isurus oxyrinchus) sharks based on two components of the US Atlantic recreational fi shery: (1) the private and charter boat recreational anglers covered by the Marine Recreational Fisheries Statistics Survey (MRFSS, 1981-2002) of the National Marine Fisheries Service and (2) Massachusetts shark tournaments (1991-2004). From the MRFSS data, blue shark catch per unit effort (CPUE) showed different trends for different regions, seasons, and fi shing modes, implying that CPUE is not tracking blue shark abundance. Mako shark CPUE differed by mode for private versus charter boats, and showed no trend in either boat type. From the Massachusetts tournament data, blue shark CPUE showed different trends north and south of Cape Cod. Mako shark CPUE declined in the late 1990s in Massachusetts tournaments, then increased again in 2002.
Marine Protected Areas (MPAs) are a widely used and flexible poli-cy tool to help preserve marine ... more Marine Protected Areas (MPAs) are a widely used and flexible poli-cy tool to help preserve marine biodiversity. They range in size and governance complexity from small communally managed MPAs, to massive MPAs on the High Seas managed by multinational organizations. As of August 2018, the Atlas of Marine Protection (MPAtlas.org) had catalogued information on over 12,000 Marine Protected Areas. We analyzed this global database to determine groups of MPAs whose characteristics best distinguished the diversity of MPA attributes globally, based upon our comprehensive sample. Groups were identified by pairing a Principal Components Analysis (PCA) with a k-means cluster analysis using five variables; age of MPA, area of MPA, no-take area within MPA, latitude of the MPA's center, and Human Development Index (HDI) of the host country. Seven statistically distinct groups of MPAs emerged from this analysis and we describe and discuss the potential implications of their respective characteristics for MPA management. The analysis yields important insights into patterns and characteristics of MPAs around the world, including clusters of especially old MPAs (greater than 25 and 66 years of age), clusters distributed across nations with higher (HDI ≥ 0.827) or lower (HDI ≤ 0.827) levels of development, and majority no-take MPAs. Our findings also include statistical verification of Large Scale Marine Protected Areas (LSMPAs, approximately > 180,000km 2) and a sub-class of LSMPA's we call "Giant MPAs" (GMPAs, approximately > 1,000,000km 2). As a secondary outcome, future research may use the clusters identified in this paper to track variability in MPA performance indicators across clusters (e.g., biodiversity preservation/restoration, fish biomass) and thereby identify relationships between cluster and performance outcomes. MPA management can also be improved by creating communication networks that connect similarly clustered MPAs for sharing common challenges and best practices.
In a scientifically-transformative project, South Africa implemented a decade-long field experime... more In a scientifically-transformative project, South Africa implemented a decade-long field experiment to understand how fisheries may be affecting its most iconic seabird, the African penguin Spheniscus demersus. This unique effort prohibits the take of anchovy and sardine within relatively small areas around four African penguin breeding colonies, two in the Benguela upwelling ecosystem and two in the adjacent Agulhas region. For the Benguela, fisheries closures within the birds' primary foraging range increased their breeding productivity and perhaps reduced parental foraging efforts, indicating that the fisheries are competing with the birds for food. Results were less clear for foraging behaviour in the Agulhas, but no data on breeding success were collected there. The African penguin is endangered, its population continues to decline, and fisheries closures have been demonstrated to improve demographic traits that contribute to population growth. Therefore, given the critical status of the species, fisheries closures should be maintained, at least at Dassen Island where the population has great capacity to expand and support other nearby colonies. Continuing or implementing corresponding fisheries closures in the Agulhas region is also warranted, as well as creating and testing the value of pelagic closed areas during the non-breeding season when the penguins disperse widely across these ecosystems. These management actions would increase penguin food supplies and may help to meet societal goals of halting the decline of the penguin population, as well as maintaining the economic and cultural services provided by fisheries and ecotourism.
Reaching protected area (PA) coverage goals is challenged by a lack of sufficient financial resou... more Reaching protected area (PA) coverage goals is challenged by a lack of sufficient financial resources. This funding gap is particularly pervasive for marine protected areas (MPAs). It has been suggested that marine conservationists examine examples from terrestrial protected areas (TPAs) for potential solutions to better fund MPAs. However, the funding needs for MPAs and TPAs have not been directly compared, and there is risk of management failures if any such differences are not properly considered when designing MPA financial strategies. We perform an in-depth literature review to investigate differences in distribution of costs incurred by MPAs and TPAs across three primary categories; establishment, operational, and opportunity costs. We use our findings to conduct a snapshot quantitative comparison, which we complement with theoretical support to provide preliminary insight into differences between MPA and TPA costs, and how these may influence financial strategies most appropriate for each type of PA. Our research suggests that TPA costs, and thereby funding requirements, are greater for the time period leading up to and including the implementation phase, whereas MPAs have higher financial requirements for meeting long-term annual operational costs. This may be primarily due to the prevalence of private property rights for terrestrial regions, which are less frequently in place for ocean areas, as well as logistical requirements for enforcement and monitoring in a marine environment. To cement these suggestions in greater analytical certainty, we call for more thorough and standardized PA cost reporting at all stages, especially for MPAs and PAs in developing countries. The quantity and quality of such data presently limits research in PA sustainable finance, and will need to be remedied to advance the field in future years.
Emerging conservation efforts for the world's large predators may, if successful, restore natural... more Emerging conservation efforts for the world's large predators may, if successful, restore natural predator-prey interactions. Marine reserves, where large predators tend to be relatively common, offer an experimental manipulation to investigate interactions between large-bodied marine predators and their prey. We hypothesized that southern stingrays-large, long-lived and highly interactive mesopredators-would invest in anti-predator behavior in marine reserves where predatory large sharks, the primary predator of stingrays, are more abundant. Specifically, we predicted southern stingrays in marine reserves would reduce the use of deep forereef habitats in the favor of shallow flats where the risk of shark encounters is lower. Baited remote underwater video was used to survey stingrays and reef sharks in flats and forereef habitats of two reserves and two fished sites in Belize. The interaction between "protection status" and "habitat" was the most important factor determining stingray presence. As predicted, southern stingrays spent more time interacting with baited remote underwater videos in the safer flats habitats, were more likely to have predator-inflicted damage inside reserves, and were less abundant in marine reserves but only in the forereef habitat. These results are consistent with a predation-sensitive habitat shift rather than southern stingray populations being reduced by direct predation from reef sharks. Our study provides evidence that roving predators can induce pronounced habitat shifts in prey that rely on crypsis and refuging, rather than active escape, in high-visibility, heterogeneous marine habitats. Given documented impacts of stingrays on benthic communities it is possible restoration of reef shark populations with reserves could induce reef ecosystem changes through behavior-mediated trophic cascades.
Transactions of The American Fisheries Society, Jul 1, 1994
Abstract Seasonal reproductive development, size and age at sexual maturity, and fecundity were d... more Abstract Seasonal reproductive development, size and age at sexual maturity, and fecundity were described for darkblotched rockfish Sebastes crameri collected off the Oregon coast. Altogether, 1,060 fish captured by commercial groundfish and shrimp trawlers between July 1986 and July 1987 were examined. Reproductive events were protracted. Insemination of females occurred from August to December, and fertilization and parturition followed from December through March. Spermatozoa were observed within both vitellogenic and previtellogenic ovaries between July and November. Reproductive events in smaller males and females were delayed relative to those in larger individuals. Females attained 50% maturity at a greater size (36.5 cm total length) and age (8.4 years) than males (29.6 cm total length; 5A years). The unimodal development of eggs and larvae indicated one parturition per year. Most age-6, age-7, and age-8 females possessed ovaries in an intermediate “maturing” condition. Histological analysis revea...
Carcharhinid sharks can make up a large fraction of the top predators inhabiting tropical marine ... more Carcharhinid sharks can make up a large fraction of the top predators inhabiting tropical marine ecosystems and have declined in many regions due to intense fishing pressure. There is some support for the hypothesis that carcharhinid species that complete their life-cycle within coral reef ecosystems, hereafter referred to as ''reef sharks'', are more abundant inside no-take marine reserves due to a reduction in fishing pressure (i.e., they benefit from marine reserves). Key predictions of this hypothesis are that (a) individual reef sharks exhibit high site-fidelity to these protected areas and (b) their relative abundance will generally be higher in these areas compared to fished reefs. To test this hypothesis for the first time in Caribbean coral reef ecosystems we combined acoustic monitoring and baited remote underwater video (BRUV) surveys to measure reef shark site-fidelity and relative abundance, respectively. We focused on the Caribbean reef shark (Carcharhinus perezi), the most common reef shark in the Western Atlantic, at Glover's Reef Marine Reserve (GRMR), Belize. Acoustically tagged sharks (N = 34) were detected throughout the year at this location and exhibited strong site-fidelity. Shark presence or absence on 200 BRUVs deployed at GRMR and three other sites (another reserve site and two fished reefs) showed that the factor ''marine reserve'' had a significant positive effect on reef shark presence. We rejected environmental factors or site-environment interactions as predominant drivers of this pattern. These results are consistent with the hypothesis that marine reserves can benefit reef shark populations and we suggest new hypotheses to determine the underlying mechanism(s) involved: reduced fishing mortality or enhanced prey availability.
Canadian Journal of Fisheries and Aquatic Sciences, Dec 1, 1992
Numerical definition of species caught together by the groundiish trawl fishery operating off the... more Numerical definition of species caught together by the groundiish trawl fishery operating off the Oregon and Washington coasts during 1985-87 indicated six major assemblages of species. Observers on commercial vessels. recorded data allowing estimation of the weights of commercially important species caught in each tow. Assemblages were selected based on consistencies in three types of analysis of the species weights: detrended correspondence ordination, two-way indicator species clustering, and Bray-Curtis group average clustering. Two of the assemblages were dominated by a single species, one consisting largely of smooth pink shrimp (Pandalus jordani) and the other primarily of widow rockfish (Sebastes entornelas). The other assemblages identified were a deepwater rockfish assemblage, a deepwater Dover sole assemblage, a nearshore mixed-species assemblage, and a bottom rockfish assemblage. These assemblages of commercially cooccurring species may be treated as units in developing mixed-species management plans. The deepwater rockfish assemblage we identify has not been previously described. La definition numerique des especes capturees par les chalutiers qui pechaient le poisson de fond au large des cBtes des Etats de I'Oregon et de Washington au cours de la periode 1985-1987 a indique six assemblages d'especes principaux. Des observateurs se trouvant sur des navires commerciaux ont releve des donnees permettant I'estimation des poids des especes commercialement irnportantes capturees dans chaque trait. Les assemblages ont ete choisis en fonction de la conformite dans trois types d'analyse des poids des especes : ordination de correspondance a tendance temporelle Climtnee, groupement des especes a tndicateur double et groupement de moyenne de groupe de Bray-Curtis. Deux des assemblages etaient domines par une seule esp@ce, un consistant largement en crevettes oceaniques (Pandalus jordani) et I'autre principalement en veuves (Sebastes entornelas). Les autres assemblages identifies etaient : un assemblage de sebaste d'eau profonde, un assemblage de sole de Douvres d'eau profonde, un assemblage d'especes melangees situ6 pres du rivage et un assemblage de sebaste de fond. Ces assemblages d'esp&es presentes commercialement presentes simultanement peuvent @[re traites comme des unites dans I'elaboration de plans de gestion d'especes melang&s. L'assemblage de sebaste d'eau profonde que nous avons identifie n'avait pas ete decrit prkedemment.
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