Fisheries Management and Ecology最新文献

The Queenfish, Scomberoides commersonnianus, is a large commercial fish in Bangladesh. This is the first study on the Queenfish that aims to elucidate life history parameters and stock status to suggest authority for sustainable management and to support future research on this economically significant species in the region. We used three length-based approaches to establish a standard for sustainable management of the fishery: (1) TropFishR to give the growth parameters and current exploitation status, (2) the length-based Bayesian biomass estimation (LBB) to quantify stock biomass, (3) and Froese's sustainability indicators (LBI). The length–weight relationship of Queenfish was a negative allometric pattern (b = 2.84; R² = 0.98). Growth parameters for Queenfish were L_∞ = 124.22 cm, K = 0.31 year⁻¹. Instantaneous total mortality Z = 0.71 year⁻¹, instantaneous natural mortality M = 0.36 year⁻¹, and instantaneous fishing mortality F = 0.35 year⁻¹. Based on the LBB approach, the current estimated stock biomass was overexploited (B/B_MSY = 0.65). We recommend strictly maintaining mesh size of nets to reduce harvest of immature fish shorter than 62 cm, while focusing harvest on fish 62–74 cm, to minimise recruitment and growth overfishing.

Acoustic telemetry (AT) has emerged as a valuable tool for monitoring aquatic animals in both European inland and marine waters over the past two decades. The European Tracking Network (ETN) initiative has played a pivotal role in promoting collaboration among AT researchers in Europe and has led to a significant increase in the number of tagged and observed aquatic animals in transboundary European waters. While AT benefits decision-making and delivers essential data to management bodies, its potential for management decision-making mechanisms has yet to be fully harnessed. We reviewed existing research, studies, and organisational initiatives related to aquatic animal tracking and their utility in fisheries management in European waters. We found that AT has already contributed to many aspects of fisheries management, such as improved understanding of stock dynamics, identification of critical habitats, assessment of migration routes, and evaluation of the effectiveness of conservation measures. However, broader utilisation of tracking technologies is needed. By leveraging the full potential of AT, managers can make more informed decisions to protect, restore, and sustainably manage European waters and creatures that live therein.

Transboundary freshwater fish are critical for both biodiversity and community well-being but face alarming overexploitation in shared rivers. Such rivers greatly aid the livelihood and nutrition of local people on both sides of shared borders. However, a lack of understanding of resource dynamics and utilization patterns hinders sustainable management of resources. We investigated spatiotemporal fish assemblages along the River Atrai, a transboundary river between India and Bangladesh. The socioeconomic status of fishers was quantified from personal interviews and group discussions to estimate the exploitation trajectory of piscine resources. Fish assemblages varied significantly among locations and seasons. Species diversity was highest downstream and lowest upstream. Spatiotemporal fishery exploitation aligned with fish diversity among sites and seasons, with fishers preferring to fish in downstream areas during the post-monsoon season. Fishers were economically weak, with limited sources of income. Therefore, adequate integrated management plans should be implemented to ensure resource resilience in a transboundary pocket, sustainably supporting the livelihood of concomitant fishers.

Streamflow, dissolved oxygen, and water temperature underpin stream fish habitat suitability, so climate change could cause widespread habitat deterioration. Identifying stream characteristics that mediate habitat resilience to heatwaves will allow conservation effort prioritisation. Here, a set of readily applied metrics were used to assess hydrological and oxythermal responses of neighbouring salmonid streams, with distinctive geologies, soil-types, and localised riparian shading, to periods of anomalously warm conditions. During heatwaves, low flows, warm-water temperatures, and diel oxygen variability, associated with biogenic production and respiration, predominated. In a low-shade stream lacking significant catchment water storage, high daytime (>22°C) and night-time (>19°C) water temperatures and low early morning O₂ concentrations (<5 mg L⁻¹) accumulated oxythermal stress for salmonids throughout summer. A stream with localised shading and a higher proportion of underlying aquifers and permeable soils throughout its watershed experienced considerably less cumulative oxythermal stress (O₂ > 6 mg L⁻¹; temperatures <19°C), whilst slower release of subsurface water bolstered base flows during dry spells. Our findings support conservation of shaded streams with permeable watersheds characterised by higher soil infiltration rates and aquifer storage capacity as salmonid sanctuaries under a warmer, drier summer climate. Preventing water quality and hydromorphological deterioration are paramount for safeguarding their role as climate refugia.

The legacy of intentional freshwater fish introductions across the western United States has fostered social tensions over the control of nonnative species in some contexts. Overcoming tensions and implementing effective control programs is important for mitigating impacts to native species. We modeled the efficacy of incentivized harvest for controlling nuisance smallmouth bass (Micropterus dolomieu) using empirical responses measured during fishing tournaments on two reservoirs that are sources of nonnative predators to critical habitat of native species. Simulations demonstrated that anglers could suppress adult smallmouth bass by 90%–99% in under 30 years, but were contingent on program participation and density dependence in harvest efficiency (i.e., catchability) and population demographics. Catchability differed between systems and varied temporally within the same system, thereby suggesting tournament structure could be adapted to increase harvest rates. Incentivized harvest should not be dismissed as a viable control strategy alone or in tandem with other methods in small lentic systems.

Catch-and-release angling is common in recreational fisheries, but post-release mortality (PRM) may be high. We conducted a controlled field experiment to estimate mortality of released snapper Chrysophrys auratus. Recreational fishers caught 960 snapper from three depth strata (<15, 15–25, 26–40 m) that were either lip-hooked, foul-hooked or gut-hooked. A bottom longline vessel caught 162 lip-hooked fish in shallow water to serve as controls. Fish were held in 15-m deep holding nets. All control fish and 80% of treatment fish survived, with anatomical hook site and capture depth significantly predicting mortality. Probability of mortality was lowest for lip-hooked fish in shallow water (5 m = 0.00, 95% CI [0.00, 0.03]), but increased rapidly to 20 m (0.24, 95% CI [0.2, 0.3]). Mortality of foul-hooked fish increased steadily with depth from 0.05 (95% CI [0.00, 0.78]) at 5 m to 0.65 (95% CI [0.13, 0.96]) at 40 m. Gut-hooking resulted in high mortality at all depths but a low sample size resulted in high uncertainty of estimates. Our results indicate that snapper PRM can be reduced by fishing in shallow water and by mitigating gut-hooking, possibly by using large circle hooks.

In the high seas, regional fishery management organisations are required to implement measures to prevent significant adverse impacts on vulnerable marine ecosystems (VMEs). Our objectives were to develop habitat suitability models for use in the spatial management of bottom fisheries in the South Pacific and to evaluate these and existing models using independent data from high-quality seafloor imagery. Presence-only models for seven VME indictor taxa were developed to complement previous modelling. Evaluation of habitat suitability models using withheld data indicated high mean True Skill Statistic scores of 0.44–0.64. Most habitat suitability models performed adequately when assessed with independent data on taxon presence and absence but were poor surrogates for abundance. We therefore advocate caution when using presence-only models for spatial management and call for more systematically collected data to develop abundance models.

The use of Pop-up Satellite Archival Tags (PSATs) has provided considerable new information about the behaviour of migrating (silver) eels (Anguilla spp.) at sea, with 9 of 19 recognised species or subspecies tagged to date. However, such studies often reported premature tag detachment and relatively high rates of predation. Since 2000, several PSAT-tagged New Zealand longfin eels, Anguilla dieffenbachii, were released to understand migratory behaviour and location of potential spawning grounds. Of 20 PSAT-tagged eels released in 2019, all tags detached prematurely, but 7 (58%) were likely eaten or injured by predators 1–81 days after release. Two eels were probably eaten by sperm whales, whereas other tagged eels were likely eaten by lamniform and non-lamniform sharks, and southern bluefin tuna. Because of the high rate of predation, we recommend that future releases should be from smaller catchments or offshore.

Blackfin tuna Thunnus atlanticus often inhabits warm waters of the western Atlantic Ocean from 40°N (Cape Cod, USA) to 22°S (Rio de Janeiro, Brazil). We recorded the first catches of the species in southern Brazil (34°S) and described its new distribution and fishing grounds. Since 2007, annual catches per trip and frequency of blackfin tuna landings increased for three oceanic fishing fleets in Southern Brazil. The spatial distribution of higher catches and the center of gravity of spatial fishing records moved poleward. Sea surface temperature anomalies for the region warmed from 1960 to 2019, and anomalies were primarily positive after 2000. Evidence suggests that the distribution of blackfin tuna moved poleward by six degrees of latitude (~660 km). The causes of this distribution extension were unclear, but ocean warming was the most likely driver.