Fisheries Management and Ecology最新文献

Recreational fisheries represent a socially, ecologically, and economically significant component of global fisheries. The U.S. Inland Creel and Angler Survey Catalog (CreelCat) database includes inland recreational fisheries survey data across the United States to facilitate large-scale analyses. However, because survey methods differ, a statistical method capable of integrating these surveys is necessary to assess patterns and relationships across regions. Here, we developed a hierarchical generalized linear mixed modeling approach to estimate the relationship between daily recreational fisheries catch and effort based on waterbody, socio-economic, and ecological covariates. We applied this approach to CreelCat data on lentic waterbodies and found that recreational fisheries catch and effort were non-linearly related (i.e., catch per unit of effort declined as effort increased), where effort varied regionally and by waterbody area, median county age, and distance to nearest primary road. This modeling approach could be used to inform data-poor regions or waterbodies, make comparisons across spatial scales, and, with the inclusion of socio-economic and ecological factors, inform management techniques in an era of shifting demographics and landscapes.

Complexity of addressing cumulative effects that vary in space and time, especially for species occupying large ranges, makes conservation and recovery of populations difficult. In Alberta, declines of all three native stream trout species led to them being listed as species at risk. We developed a novel, semi-quantitative cumulative effects modelling process to quantify threats using stressor-response curves with a single common response scale, wherein inputs were determined for each population, and outputs were used to create population-specific recovery action hypotheses to inform management. Using a case study of bull trout recovery in Rocky Creek, Alberta, we tested these hypotheses using a before–after control-impacted design. Recovery actions positively affected bull trout, and the modelling approach provided insight into threats (sedimentation and angling effort) that most likely limited the population.

Motorized trawling was banned off part of the Brazilian coast in 1990 due to environmental impacts, thus artisanal fishermen adopted large beach seines as an alternative. No impact assessments have been conducted on any species; therefore, we examined the life history and stock status of shorthead drum, Larimus breviceps, a primary bycatch in tropical shrimp fisheries. Between 2016 and 2017, 969 shorthead drum were collected and analyzed using ELEFAN-based models. Females were larger, more abundant, and older than males. Capture rates of juvenile were high, and no mega-spawners were found. Integrated stock assessment indicated slight overexploitation and growth overfishing. Increased yield per recruit was indicated by high length at first capture. Shorthead drum segregate ontogenetically by size. Growth, mortality, and longevity may be temperature-influenced. We found that beach seine fisheries may impact shorthead drum by population depletion and potential disruptions to reproductive capacity and recommend further studies and management to improve sustainability.

The Arctic charr (Salvelinus alpinus) is a species of cultural, economic and conservation importance, but hitherto, investigations of critical early life stages have been few. Here, at a lake in the United Kingdom, we used swim-up traps to investigate the phenology of fry emergence and associations between fry density and habitat. The first emergence occurred on 4 or 5 March 2020 and 2021, with numbers peaking and remaining stable in the following 2 weeks. Emergence in 2021 had finished by 27 March but on the same date in 2020 emergence was ongoing when COVID-19 ended sampling. Substrate particle size ranged 31–94 mm and was negatively correlated with fry density. Likewise, density was negatively correlated with water depth and aquatic plant cover, but there was no relationship with flow velocity. Traps were effective and non-destructive for assessing the location and productivity of spawning sites for this locally threatened species.

American Eel (Anguilla rostrata) population characteristics and distribution remain drastically understudied in the Caribbean region. We conducted the first island-wide study to evaluate the distribution of density, length, and sex in relation to distance from the mouth of 23 stream reaches in five rivers in Puerto Rico. We found 287 American Eel at a mean density of 156.7 fish/ha. Sex ratios favored females (52:3) but most of the eel sampled were undifferentiated or undetermined. Generalized linear modeling indicated that upstream habitats with low eel density were optimal environments for production of large and female eel. Our findings indicate that Puerto Rico could significantly contribute to the spawning population and strengthen knowledge of American Eel in the Caribbean. Our findings could be used to guide local and range-wide conservation efforts to ensure stream connectivity and access to optimal upstream habitat for survival of the population.

Hatcheries have long produced salmonids for fisheries and mitigation, though their widespread use is increasingly controversial because of potential impacts to wild salmonids. We conducted a global literature search of peer-reviewed publications (1970–2021) evaluating how hatchery salmonids affected wild salmonids, developed a publicly available database, and synthesized results. Two hundred six publications met our search criteria, with 83% reporting adverse/minimally adverse effects on wild salmonids. Adverse genetic effects on diversity were most common, followed by effects on productivity and abundance via ecological and genetic processes. Few publications (3%) reported beneficial hatchery effects on wild salmonids, nearly all from intensive recovery programs used to bolster highly depleted wild populations. Our review suggests hatcheries commonly have adverse impacts on wild salmonids in freshwater and marine environments. Future research on less studied effects—such as epigenetics—could improve knowledge and management of the full extent of hatchery impacts.

The migratory behavior and spawning of Curimatá-pacu (Prochilodus argenteus) were assessed in a free-flowing remnant spanning approximately 450 km. This evaluation was conducted using radio-tagging and egg sampling, with identification performed through metabarcoding techniques. Among the studied individuals, half migrated 100–365 km upstream, primarily in response to the initial rise in river discharge at the onset of the wet season. Conversely, the remaining fish did not exhibit upstream movement, indicating a partial migratory behavior. The presence of eggs exclusively in the headwaters suggests that breeding occurred solely among fish inhabiting the upstream sites. The observed migratory traits resembled those of other congeneric species.

We sought to demonstrate how eel mortality, growth, and biomass production were related to initial stocking density of glass eels, 18 months after stocking. Glass eels with a mean body mass of 0.29 g were caught in three coastal streams of Denmark, and subsequently stocked at four densities (0.5, 1, 1.5, and 2 individuals m⁻²) in eight shallow, 200 m², open ponds. Recapture after 18 months ranged from 13% to 84% and was negatively correlated with stocking density. Likewise, growth (length and body mass) and body condition were negatively correlated with stocking density. The theoretical maximum biomass per stocked glass eel was 7.3 g at a density of 0.005 eels per m⁻² (one glass eel per pond), and the minimum was at a density of 3 glass eel m⁻² (600 glass eels per pond). The optimum eel biomass was 3.9 g m⁻² at a stocking density of ≈1 glass eel m⁻², which probably represented the present production capacity (food) of these ponds.

The Acoupa weakfish, Cynoscion acoupa, is an important fishery resource of the Brazilian North coast that is commercially valuable, particularly for its gas bladder (fish maw), which is exported to Asian markets. However, because of intensive fishing and lack of reliable data, the Acoupa weakfish is classified as Vulnerable by the IUCN. We used Fisheries Performance Indicators (FPIs) to evaluate C. acoupa fisheries on the Amazon continental shelf, to inform management actions. The ecological indicator had the lowest score due to increased fishing effort associated with high demand for the fish maw, and the co-management indicator was also unsatisfactory due to the predominance of fishing entrepreneurs and a lack of sustainable management practices. Our findings showed that the C. acoupa fishery is precarious in its sustainability, mainly because of harvest and co-management which were the least satisfactory metrics.