106 research outputs found
Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Southwest): Black, green, and red abalones
All abalones belong to the genus
Haliotis sensu latu, family Haliotidae.
The 75 species known worldwide
(Booloot ian et, al. 1962) are anatomically
similar and all are adapted for
attachment to hard substrates. Seven
species are widely distributed along
the coast of California (Cox 1962;
Mottet 19781, of which several are
important in the comercial and sport
fisheries of the Pacific Southwest. (PDF has 19 pages.
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Economic Assessment of the Biological Dynamics of Florida’s Commercial Snapper-Grouper Fishery
The goal of this research was to characterize the trade-offs between profitability and sustainability when managing a valuable commercial fishery. The Florida finfish fishery generates over $75 million in annual dockside value; the snapper-grouper complex constitutes over half of that total. Currently, federal stock assessment procedures focus on stock size and effort constraints, but lack any economic specificity associated with proposed regulatory actions. To evaluate management strategies for snappers and groupers, an age-structured bioeconomic model was created for half a dozen snappers and groupers that dominate the commercial catch vector. Prices per pound of these snappers and groupers were estimated using domestic landings and imports, then linked to dynamic biological-economic production models. Management scenarios including eumetric fishing, which optimizes yield per recruit by adjusting minimum size limits and fishing mortalities, were simulated to examine the sensitivity of tradeoffs between economic returns and long-term fishery sustainability. An increase in minimum size limits causes a temporary decrease in domestic landings to allow for spawning stock biomass to rebuild. Since grouper production is primarily domestic, the price per pound would increase during the rebuilding phase; however, since snapper production is primarily imported, the decrease in domestic catches would have no influence on price per pound. These results imply that market elasticity surrounding grouper production will buffer the economic hardship of decreased catch, while snappers’ inelastic market may require more intricate management intervention
Regional differences in an established population of invasive Indo-Pacific lionfish (Pterois volitans and P. miles) in south Florida
About nine years ago (circa 2009), Indo-Pacific lionfishes (Pterois volitans and P. miles) invaded the south Florida coral reef ecosystem. During the intervening period of time, there has been substantial research on their biology, life history, demography, and habitat preferences; however, little is known concerning their regional population status and trends in the region. Here, we use a large-scale fisheries independent reef fish visual survey to investigate lionfish population status among three south Florida regions: Dry Tortugas, Florida Keys, and southeast Florida. Density estimates (ind ha−1) have been relatively stable since 2012, and are lower than other areas reported in the western Atlantic and Caribbean Sea. Low, stable population densities in south Florida suggest there may be a natural mechanism for lionfish population control. In the Dry Tortugas, lionfish density in 2016 was significantly lower (0.6 ind ha−1 ± 0.15 SE) than the two other south Florida regions. The Dry Tortugas region has the highest percentage of marine protected areas, the lowest level of exploitation, and thus the highest densities of potential lionfish predators and competitors. In the Florida Keys and southeast Florida in 2016, lionfish densities were greater (5.4 ind ha−1 ± 1.0 SE and 9.0 ± 2.7 SE, respectively) than the Dry Tortugas. Fishing pressure on lionfish was higher in these two regions, but densities of several potential predators and competitors were substantially lower. Despite relatively low regional lionfish densities that can be attributed to some combination of fishing mortality and natural biocontrol, lionfish are still well established in the south Florida coral reef ecosystem, warranting continued concern
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A retrospective bioeconomic assessment of Florida’s commercial reef fisheries
The Florida reef ecosystem is a highly valuable resource managed by multiple federal and state agencies with many stakeholders. Over half of the $75 million annual dockside value of finfish landings in Florida is comprised of snappers and groupers, but this resource is threatened by overfishing. Current management strategies include annual catch limits, spatial closures, seasonal closures, size limits, limited-entry, and catch shares. To investigate the performance of rebuilding strategies for a number of snapper-grouper species, we developed an age-structured, multi-fleet bioeconomic model. First, sustainability status was estimated via a length-based assessment, and observed total catch validated the simulated age-structured production model. After estimating seafood demand as a function of domestic landings, imports, disposable income, and management regimes, we estimated fleet costs as a function of effort, vessel characteristics, and permit type. Building on the above relationships, we conducted a retrospective analysis that examined the bioeconomic consequences of past management actions relative to a suite of rebuilding policies. Simulated policies focused on adjusting minimum size limits to maximize yield-per-recruit and were ranked based on economic output. The larger simulated fish stocks were associated with lower costs for the same amount of revenue (higher catch-per-unit-effort), a more stable resource, and larger long-term monetary gains. Our retrospective analysis estimates forgone economic surpluses from non-aggressive rebuilding actions and provides alternative strategies for future management
Rapid Invasion of Indo-Pacific Lionfishes (\u3cem\u3ePterois Volitans\u3c/em\u3e and \u3cem\u3ePterois Miles\u3c/em\u3e) in the Florida Keys, USA: Evidence from Multiple Pre- and Post-Invasion Data Sets
Over the past decade, Indo-Pacific lionfishes, Pterois volitans (Linnaeus, 1758) and Pterois miles (Bennett, 1828), venomous members of the scorpionfish family (Scorpaenidae), have invaded and spread throughout much of the tropical and subtropical northwestern Atlantic Ocean and Caribbean Sea. These species are generalist predators of fishes and invertebrates with the potential to disrupt the ecology of the invaded range. Lionfishes have been present in low numbers along the east coast of Florida since the 1980s, but were not reported in the Florida Keys until 2009. We document the appearance and rapid spread of lionfishes in the Florida Keys using multiple long-term data sets that include both pre- and post-invasion sampling. Our results are the first to quantify the invasion of lionfishes in a new area using multiple independent, ongoing monitoring data sets, two of which have explicit estimates of sampling effort. Between 2009 and 2011, lionfish frequency of occurrence, abundance, and biomass increased rapidly, increasing three- to six-fold between 2010 and 2011 alone. In addition, individuals were detected on a variety of reef and non-reef habitats throughout the Florida Keys. Because lionfish occurrence, abundance, and impacts are expected to continue to increase throughout the region, monitoring programs like those used in this study will be essential to document ecosystem changes that may result from this invasion
Ecological-economic assessment of the effects of freshwater flow in the Florida Everglades on recreational fisheries
This research develops an integrated methodology to determine the economic value to anglers of recreational fishery ecosystem services in Everglades National Park that could result from different water management scenarios. The study first used bio-hydrological models to link managed freshwater inflows to indicators of fishery productivity and ecosystem health, then link those models to anglers\u27 willingness-to-pay for various attributes of the recreational fishing experience and monthly fishing effort. This approach allowed us to estimate the foregone economic benefits of failing to meet monthly freshwater delivery targets. The study found that the managed freshwater delivery to the Park had declined substantially over the years and had fallen short of management targets. This shortage in the flow resulted in the decline of biological productivity of recreational fisheries in downstream coastal areas. This decline had in turn contributed to reductions in the overall economic value of recreational ecosystem services enjoyed by anglers. The study estimated the annual value of lost recreational services at 11.88 per AF in November to 41.54 per AF. Linking anglers\u27 recreational preference directly to a decision variable such as water delivery is a powerful and effective way to make management decision
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Benthic Habitat Mapping in the Tortugas Region, Florida
Concern about declining trends in coral reef habitats and reef fish stocks in the Florida Keys contributed to the implementation of a network of no-take marine protected areas in 1997. In support of the efforts of the Dry Tortugas National Park and Florida Keys National Marine Sanctuary to implement additional no-take areas in the Tortugas region in 2001, we expanded the scale of our fisheries independent monitoring program for coral reef fishes in the region. To provide a foundation for the habitat-based, stratified random sampling design of the program, we created a digital benthic habitat map of coral reef and hard-bottom habitats in a geographic information system by synthesizing data from bathymetric surveys, side-scan sonar imagery, aerial photogrammetry, existing habitat maps, and in situ visual surveys. Existing habitat maps prior to 1999 were limited to shallow-water (\u3c 20 m depth) soft-sediment, coral reef, and hard-bottom habitats within Dry Tortugas National Park and did not include deeper areas such as the Tortugas Bank, now partially contained within no-take marine protected area boundaries. From diver observations made during the 1999 survey, we developed a classification scheme based on habitat relief and patchiness to describe nine hard-bottom and coral reef habitats encountered from 1-33 m depth. We provide estimates of area by habitat type for no-take marine protected areas in the Tortugas region. Updated information on the spatial distribution and characteristics of benthic habitats will be used to guide future monitoring, assessment, and management activities in the region. Significant data gaps still exist for the western area of the Florida Keys National Marine Sanctuary and are a priority for future research
Assessing Coral Reef Fish Population and Community Changes in Response to Marine Reserves in the Dry Tortugas, Florida, USA
The efficacy of no-take marine reserves (NTMRs) to enhance and sustain regional coral reef fisheries was assessed in Dry Tortugas, Florida, through 9 annual fishery-independent research surveys spanning 2 years before and 10 years after NTMR implementation. A probabilistic sampling design produced precise estimates of population metrics of more than 250 exploited and non-target reef fishes. During the survey period more than 8100 research dives utilizing SCUBA Nitrox were optimally allocated using stratified random sampling. The survey domain covered 326 km2, comprised of eight reef habitats in four management areas that offered different levels of resource protection: the Tortugas North Ecological Reserve (a NTMR), Dry Tortugas National Park (recreational angling only), Dry Tortugas National Park Research Natural Area (a NTMR), and southern Tortugas Bank (open to all types of fishing). Surveys detected significant changes in population occupancy, density, and abundance within management zones for a suite of exploited and non-target species. Increases in size, adult abundance, and occupancy rates were detected for many principal exploited species in protected areas, which harbored a disproportionately greater number of adult spawning fishes. In contrast, density and occupancy rates for aquaria and non-target reef fishes fluctuated above and below baseline levels in each management zone. Observed decreases in density of exploited species below baseline levels only occurred at the Tortugas Bank area open to all fishing. Our findings indicate that these NTMRs, in conjunction with traditional fishery management control strategies, are helping to build sustainable fisheries while protecting the fundamental ecological dynamics of the Florida Keys coral-reef ecosystem
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