Marine and Coastal Fisheries最新文献

Game fish populations in North America face increasing pressure from recreational anglers, yet sublethal effects from mandatory catch-and-release regulations remain unknown for many targeted species. In southern California, Kelp Bass Paralabrax clathratus populations have significantly declined in recent decades, prompting changes in management and increasing release rates. To assess acute effects of current fishing regulations, we collaborated with recreational anglers to evaluate short-term, sublethal impacts of capture stress on Kelp Bass physiology and behavior. To evaluate the timeline and magnitude of physiological stress, blood samples were collected at time points (10–120 min) after angling and confinement and compared to control fish sampled in less than 3 min. Postrelease recovery was determined by comparing biomarker levels between control fish and recaptured fish that were rapidly sampled after a time at liberty ranging from 3 h to 186 d. Biomarker levels in fish recaptured multiple times were compared to previous samples to evaluate repetitive angling effects on physiological responses. Circulating cortisol, glucose, and lactate were elevated and steadily increased in the hour after capture, although angling duration and handling duration were not correlated with biomarker response. Fish size significantly affected fish stress, with larger fish experiencing less stress and rapid recovery within 24 h. Behavioral control fish, which ingested acoustic accelerometers hidden inside bait, exhibited strong diel activity that was reduced for 30 h in angled fish. Tracked individuals exhibited high individual variation in rate of movement and area use, with no noticeable postrelease impacts. Although this study found Kelp Bass to be resilient to angling stresses, evaluation of long-term effects from catch and release is warranted. This fishery may also benefit from slot limit regulations, improved angler engagement programs, and education on best practices that minimize fish stress during catch and release.

Stock assessments of U.S. Atlantic Wolffish Anarhichas lupus are hampered by a landings moratorium and low catches in fishery-independent surveys. Working with the commercial fishing industry, we collected hundreds of fish to overcome a lack of regionally specific life history information. Based on ages from sectioned otoliths, Atlantic Wolffish are long lived (maximum observed age: males = 31 years, females = 29 years). A Gompertz growth model showed that Atlantic Wolffish exhibit dimorphic growth—with larger males across all ages on average. Preliminary estimates of total mortality ranged from 0.15 to 0.21 and were lower than an estimate measured at the beginning of the moratorium. Based on gonad histology, a cohort of vitellogenic oocytes emerged in mature females by April and developed group synchronously to ovulate primarily in October. Skip spawning, which accounts for nonannual spawning, was observed in 5.6% of the mature females. Accounting for abortive maturation, a physiological event that delays functional maturation, improved precision and reduced bias of maturity estimates. The resulting median length at functional maturity was 53 cm total length (95% confidence interval = 49–56 cm), and the median age was 6.7 years old (6.2–7.2 years). These estimates are smaller and younger than elsewhere in the western North Atlantic Ocean, confirming that regionally specific maturity parameters are relevant when assessing reference points of the U.S. Atlantic Wolffish fishery.

Cusk Brosme brosme are fished across the northern Atlantic Ocean, but even basic biological data are limited in part by their difficult-to-sample deep and structured habitats. We sampled fish from a variety of sources across the Gulf of Maine to provide comprehensive life history information (age and size at maturity, fecundity, sex ratio, growth) for this data-poor species considered by National Oceanic and Atmospheric Administration Fisheries as a species of concern. Gonad histology and gonadosomatic index data indicated peak spawning in late spring (May–June), with limited spawning activity into summer. The histologically derived length at 50% maturity for female Cusk was 39.5 cm TL. Fecundity varied from a quarter million to four million oocytes, with a positive allometry versus size indicating that larger females have proportionally higher fecundity than smaller females. Male Cusk had unusually low gonadal investment for a gadiform, and males of all sizes examined (down to 21 cm) had spermatozoa present. Male maturity was equivocal even when the relative proportions of sperm stages were quantified through image analysis of gonad histology; further anatomical and physiological studies of small males are required to assess functional maturity in male cusk. The sex ratio at length indicated more males at larger sizes, and males had faster growth and larger size at age than females. Condition patterns also suggested lower condition for females than males after spawning and generally less variable condition for males. Gonadal investment, relative condition, and growth patterns all suggest differences in energy allocation between the sexes. This data-poor species has an uncertain stock status in U.S. waters; therefore, the results of the current work provide important information to its management.

Stock assessments are particularly resource-intensive processes. Demand for assessments typically exceeds capacity, stimulating interest in reducing stock assessment frequency for suitable species. Species with slow population growth rates, low economic importance, and low recruitment variability, like coastal sharks in the USA, have been identified as appropriate candidates for long-interim assessment periods. We conducted a Stock Synthesis–based management strategy evaluation with a threshold harvest rate control rule within the southeastern USA to assess the impact of stock assessment frequency for the slow-growing Sandbar Shark Carcharhinus plumbeus. Stock assessments for the Sandbar Shark in the southeastern USA have been conducted or updated every 4–6 years since 1998. The Sandbar Shark proved to be a particularly good candidate species for reduced assessment frequency, as noted by unaffected management procedure performance across interim periods of 1, 5, and 10 years. Management objectives, including probability of stock recovery, relative biomass level, cumulative U.S. commercial catch, and probability of overfishing, were minimally adversely impacted with interim periods equal to 15 years. Based on our findings, assessment frequency for large coastal shark species could reasonably be reduced in the future to once every 10 or more years without compromising management success.

Monitoring data is important in ecological research, but differences between and within areas or species in data collection methods could introduce bias in the analyses. Standardizing data collection is particularly important when monitoring migratory species that have a distribution that crosses several national borders. The European Eel Anguilla anguilla is an extreme example of such a species since it constitutes one stock across the entire distribution area. One important variable collected for the European Eel is maturation stage. This data is needed to monitor silver eel escapement to assess population trends. To determine maturation, data on length, weight, diameter of the eyes, and pectoral fin length are used to calculate Pankhurst eye index and Durif's silver index. In this study, we investigated effects of precision and interobserver variability on data collection relevant for maturation stage determination according to Pankhurst and Durif's indices. We found that eye diameter differed in size between the left and right eyes; however, the mean difference (0.19 mm) is probably an artifact of the large sample size (n = 16,977) and can be regarded as being within the measurement precision. Meanwhile, there was no significant difference in pectoral fin length. These results suggest that either side of the eel could be used without losing precision. Visually determined maturation stage classifications differed from those calculated with Pankhurst and Durif's indices but could still provide useful information; hence, it is recommended to collect this variable. Measurements performed using computer software generated greater precision than using calipers, which increased interobserver variability. Since the difference was relatively small and since computer analysis of images may not always be an option, measuring method can be decided based on the level of precision needed in each case. These suggested implementations can reduce observation bias and streamline the data collection used for stock assessments of the European Eel.

Meteorological disturbances, such as hurricanes, can cause wide distributional changes to fish populations, but studies documenting fish movement in response to these disturbances are rare and serendipitous. We opportunistically examined how a hurricane influenced behavior of Red Snapper Lutjanus campechanus at an artificial reef complex in the western Gulf of Mexico. Red Snapper had a variety of responses, with some fish emigrating and some remaining on site during Hurricane Harvey—a category 4 storm. Hurricane-induced destruction or alteration of habitat may alter space use behavior of fish. However, caution should be used when interpreting behavior without the inclusion of array performance, which may change due to environmental conditions. Importantly, when acoustic array efficiency was not accounted for in space use analyses, mean kernel utilization distribution (m³) was marginally different among the periods before, during, and after Hurricane Harvey. However, when mean daily array efficiency was included as a covariate, space use among the three periods was not significantly different. Hurricanes can affect the movement and residency of marine species and can be an important driver in the displacement of populations and degradation of habitats, but array efficiency should be incorporated to prevent misinterpreting the behaviors of tagged fish.

Biological parameters relating to the reproductive biology of Conguito Sea Catfish Cathorops liropus were investigated in 1979–1984 and 2015–2018 from an estuarine system on the northwestern Pacific coast of Mexico. In the first period, the spawning season occurred during the dry–warm season (April–June), according with the percentage of mature females and the highest gonadosomatic index (GSI) values. Mean TL was 12.3 cm, two cohorts were found, length at maturity was 18.6 cm, and fecundity was 24.47 oocytes/organism. In the second period, the spawning season extended to the rainy–warm season (July–November), as reflected by the percentage of mature females and the GSI values. Mean TL was 11.6 cm, length at maturity decreased to 17.1 cm, and fecundity decreased to 20.67 oocytes/organism, indicating a reduction in the size-based indicators and a change in the spawning period and reproductive effort as time passed. The number of fishing skiffs increased from 1,103 in 1980 to 2,434 in 2019, representing a 220% increase, and the landings increased from 400 to 3,432 metric tons in the same period. Temporal trends in surface water temperature, salinity, and the Oceanic Niño Index did not explain the observed changes between the study periods. These results suggest that the observed changes in the reproductive potential of Conguito Sea Catfish have been at least partially due to fishing.

As climate change accelerates and fisheries management continues to evolve, California's commercial fisheries are changing. To improve the understanding of recent California fisheries dynamics, we compiled and analyzed commercial landings receipts to characterize temporal and spatial variation in landing and value of key fisheries groups within the exclusive economic zone across the state from 2005 to 2019. We found that California fisheries continue a shift first observed in the 1980s from higher-biomass, lower-value species, such as coastal pelagic species and market squid, toward lower-biomass, higher-value species, such as Dungeness crab Cancer magister and groundfish. Over the 15-year time series analyzed, total landings declined by nearly two-thirds but total value remained relatively stable, likely due to a focus on higher value species and rising prices. The northern half of the state has become much more economically valuable, accounting for over 50% of total value across the state in 2019. A case study analysis found groundfish to be the dominant fisheries in the two areas that have been identified as priorities for potential offshore wind development in central and northern California. Our results elucidate the most recent status and trends of California's commercial fisheries, over time, across space, and among different fisheries groups, providing valuable information for informing fisheries management and marine spatial planning.

Sensitivity analyses have identified uncertainty regarding sex ratios within commercial landings of Pacific Halibut Hippoglossus stenolepis as an influential source of variance within annual stock assessments for this species in U.S. and Canadian waters. Sex composition of dockside landings cannot be directly observed because all retained fish must be eviscerated at sea, and sex cannot be visually determined in the absence of the gonads. In the current study, a marking program was evaluated in which sex-specific marks were applied by fishers to their retained catch, the mark was recorded during dockside monitoring, and the accuracy of the recorded sexes was validated using genetic techniques. The chosen marks (two vertical cuts in the dorsal fin for females and a single cut in the operculum of males) were considered by fishers to be easy to apply during at-sea processing and produced sex-ratio estimates that were equivalent to genetic results for 65% of sampled landings. However, vessel- and region-specific accuracy was variable. Additional incentives to encourage vessels to participate in the program, continued outreach, or potentially a regulatory requirement to mark fish would be required to produce sufficient data to satisfy stock assessment needs, and ongoing validation would likely need to accompany such a program to ensure consistent and acceptable data quality.

The reproductive biology of the heavily exploited Pacific Spadenose Shark Scoliodon macrorhynchos was studied by examining 246 males and 197 females, including 64 gestational individuals, caught by semi-industrial fisheries using demersal trawling in the southern Taiwan Strait. Total length (L_T) at 50% maturity (L₅₀) was estimated at 464 mm L_T for males and 429 mm L_T for females. The annual reproductive cycle was determined based on the percentage of pregnant mature females and the concurrent vitellogenesis with embryonic development. Mating occurred from August to December, as evidenced by the presence of females with fresh mating injuries on their body surface and spermatozoa in the cloaca and uteri. The monthly change of embryo size indicated that parturition occurred between June and August after 5–6 months of gestation, with an L_T of 190–218 mm at birth. The litter size, which ranged from 1 to 20 pups with a mean ± SD of 9.4 ± 3.9 pups (n = 64), was positively correlated with the maternal L_T. Altogether, these findings provide valuable information that is needed for the adequate management and conservation of Pacific Spadenose Sharks in the southern Taiwan Strait and adjacent waters.