Fisheries Oceanography最新文献

Disentangling the roles of fishing and environmental factors in fish stock dynamics is fundamental for sustainable fisheries management. The stock biomass of Norwegian coastal cod north of 67°N has varied between periods of increase and decline in recent decades, with declining biomass since 2014. Here we developed a population model for the dynamics of this stock. The model was statistically fitted to survey indices of abundance- and length-at-age and environmental covariates from 1995 to 2022. The final model included a negative effect of saithe biomass on survival to age 1, positive temperature effects on growth to ages 2 and 3, density dependence in survival and growth, size-dependent maturation, and negative fishery effects on adult survival. Hindcast scenario simulations, where environmental influences or mortality from fishing were fixed, were used to disentangle the roles of recruitment, growth and adult survival for stock fluctuations in recent decades. The changes in stock biomass appear mainly to be driven by adult survival and hence fishing. The fishery effects on stock biomass were mostly the direct effects of biomass removal, with no indication of fishery-caused recruitment failure at the spatial scale represented by the model.

Variability in larval transport has long been hypothesized to drive recruitment fluctuations in fishes, yet evidence for these hypotheses is often lacking. Further, the origins of many of these hypotheses come from temperate to subpolar regions, leaving such questions largely underexplored for other regions, especially the tropics. To assess drivers of larval transport in a tropical archipelago, we simulated the dispersal of a culturally and commercially important bottomfish, uku (Aprion virescens), from Penguin Bank, its most prominent spawning location in the main Hawaiian islands. We used Lagrangian particle tracking models forced by a regional ocean model to assess the degree of interisland potential connectivity from this spawning location and the drivers of interannual variability in this potential connectivity across 13 years from 2008 to 2020. Simulated uku larvae released from Penguin Bank primarily reached Maui Nui and Oʻahu, the nearest potential settlement areas, with lower potential connectivity to more distant regions. Interannual variability in overall number of connections was pronounced and linked both to local wind speed and direction, with increased particle loss occurring during higher overall wind speeds and more northerly winds. Recruitment deviations from the stock assessment of uku showed a similar pattern, with recruitment estimates significantly decreasing during years of strong northerly winds. Our results provide evidence, derived from a simulation model integrating ecological and physical components, of larval dispersal patterns contributing to the recruitment of a socioeconomically important species and sensitivity of these patterns to local wind forcing. Understanding how these wind patterns will change in a warming climate may be essential to understanding patterns in uku recruitment in coming years.

Semi-enclosed seas present complex and nonlinear challenges to understanding climate impacts on fisheries because continental margins restrict poleward movement by taxa seeking to maintain preferred temperatures. The Gulf of Mexico (GoM), a semi-enclosed, marginal sea surrounded by the North American continent, supports many economically and ecologically important demersal species. A comprehensive assessment of GoM demersal environments is vital to understanding and predicting potential distribution shifts by such taxa. Here we present a Gulf-wide, interannual spatial evaluation of bottom temperature trends between 1996-2012. We validated and used bottom temperature products from a regional reanalysis with 24-h temporal and 1/25° spatial resolution (33,159 grid cells and 6209 days). Ordinary least-squares and autoregressive models estimated temporal trends and uncertainty, and optimized hot spot analyses identified spatial locales of anomalies. Bottom water cooling occurred along the West Florida Shelf, Florida Keys, northwest Cuba, and the Tamaulipas-Veracruz Shelf. Warming trends dominated the Bay of Campeche and Louisiana–Texas Shelf. Highest warming and cooling rates were 0.25 (± 0.011)°C year⁻¹ (uncertainty as 95% confidence; located in the Campeche subregion) and −0.12 (± 0.015)°C year⁻¹ (located in the Florida Keys), respectively. Increased duration of Loop Current impingement on the “pressure point” near the Dry Tortugas may drive the observed cooling trends in the eastern GoM, whereas warming trends likely arise from mixing of shallow surface waters. This study highlights the importance of spatiotemporal bottom temperature analyses in complex semi-enclosed seas where bottom temperature trends may be counterfactual to the long-term surface warming narrative.

The expansion of offshore wind interests in US waters has raised concern over potential adverse impacts to fisheries activity and productivity. Yet evidence-based platforms for assessing those impacts are lacking for many recreational fisheries. We demonstrate how data from a federal fishery survey (Large Pelagics Intercept Survey [LPIS]), cooperative tagging programs, and the direct survey of recreational fishermen can be used to characterize the spatial extent of baseline (pre-construction) effort in a recreational fishery that targets highly migratory fishes (HMS) in US territorial waters of the Atlantic, Gulf of Mexico, and Caribbean. To document the location of effort, LPIS catch data and tag, release, and recapture (CTR) records from four cooperative tagging programs were independently aggregated onto a grid of offshore wind lease blocks. An online survey of recreational fishermen was also executed to assess the spatial extent of effort in relation to a Draft Call Area (DCA) in the Gulf of Maine region. Collectively, the LPIS and CTR data described widespread recreational fishing effort for HMS, including within and around the majority of existing and planned offshore wind lease areas. Responses to the online survey revealed more widespread effort within the Gulf of Maine DCA than both the LPIS and CTR data, but some respondents may have overrepresented true levels of fishing effort. Our results demonstrate the need for multiple data types to comprehensively assess offshore wind impacts on the recreational HMS fishery and to inform marine spatial planning in regions into which offshore wind energy development may be expanded.

Flying fish (family Exocoetidae) play an important role in marine food webs, linking sub-surface and aerial predators. The association of seabirds with sub-surface predators in subtropical and tropical regions through facilitated foraging events is a well-known phenomenon and is sometimes used to identify fishing grounds for flying fish, flying fish roe, and tunas. In the northern Gulf of Mexico (nGoM), few studies have assessed flying fish distribution, and none have directly evaluated flying fish–seabird co-occurrence. Using vessel-based observations of surfacing flying fish flights, we characterized the distribution of flying fish and their co-occurrence patterns with seabirds in the nGoM. We modeled the distribution and relative density of flying fish flights using Generalized Additive Models. We then assessed co-occurrence patterns of flying fish with all seabird species seen in the area, encompassing the footprint of flying fish detections. Flying fish were detected across the U.S. Exclusive Economic Zone, with flight densities greater on the mid-continental shelf and into pelagic waters south of Louisiana, and greater flight densities were associated with regionally low chlorophyll-a and warm water. Flying fish flights were greatest in spring months through early fall months. Sooty terns (Onychoprion fuscatus), considered near-obligate commensals with tuna, contributed a much higher percent of the cumulative density of the seabirds co-occurring with versus without flying fish. Flying fish could be an ecological attractant for high abundances of visually conspicuous sooty terns, the presence of which may lead to the formation of ephemeral facilitated foraging events consisting of mixed-species seabird flocks.

Offshore wind energy has expanded as a source of clean energy in the United States since the first US offshore wind farm began operations off the coast of Rhode Island in 2016. The emergence of offshore wind has increased the need to manage ocean use across multiple stakeholder groups, a difficult and contentious process. We use 15 years of scallop (Placopecten magellanicus) fishery data to describe how offshore wind may expose one of the most valuable commercial fisheries in the United States to economic risks. Our analysis shows that the current configuration of approved offshore wind lease areas off the northeastern coast of the United States is expected to result in relatively small economic exposure for the scallop fishery. We also illustrate how the measured development process, which includes ample opportunity for stakeholder input, has mitigated exposure through minimization or avoidance by characterizing the change in impacted activity through two case studies. We find moderate to strong levels of exposure mitigation across our three scallop fleet métiers within the Central Atlantic (CA) region. In contrast, exposure mitigation was more variable in the New York Bight (NYB) region suggesting mitigation methods in the NYB are not as effective for the scallop fishery as the CA. The open development process that allowed for early stakeholder engagement has largely mitigated the potential for economic risk of offshore wind on the scallop industry by approving the siting of offshore wind development in less utilized or less productive scalloping areas.