Search

Managers of recreational fisheries often rely on implicit and rarely tested assumptions regarding how fishing effort will change in response to regulations. For instance, they assume that reduced seasons will directly reduce fishing effort without producing angler behavioral adaptations to maintain fishing opportunities and harvest. Vessel trip reports from a multi-species for-hire fishery in New Jersey, USA, allowed us to empirically evaluate changes in fishing effort as overlapping seasons for four species became shorter and as possession limits decreased. We conducted focus groups with fishery stakeholders and then developed statistical models to evaluate hypotheses describing how anglers aboard for-hire vessels adapted to regulations. Fishing effort aboard charter boats remained consistent and primarily responded to the availability of 'something' to harvest, suggesting that their customers are willing to substitute target species. Party boat anglers, in contrast, responded to the possession limits of black sea bass (Centropristis striata) and summer flounder (Paralichthys dentatus). Because party anglers were less willing to substitute target species, party vessel operators are likely particularly vulnerable to reductions in fishing opportunity and harvest potential. Les gestionnaires de peches sportives emploient souvent des hypotheses implicites et rarement validees concernant l'incidence sur l'effort de peche des reactions a la reglementation. Par exemple, ils postulent souvent que des saisons ecourtees reduisent directement l'effort de peche sans entrainer d'adaptations du comportement des pecheurs visant a maintenir les occasions de peche et les prises. Les rapports de sortie d'embarcation pour une peche multiespece a forfait au New Jersey (Etats- Unis) ont permis une evaluation empirique des variations de l'effort de peche au fil du raccourcissement des saisons de peche de quatre especes qui se chevauchent et de la reduction des limites de possession. Nous avons organise des groupes de discussion avec des parties prenantes a cette peche, puis elabore des modeles statistiques pour evaluer differentes hypotheses qui decrivent comment les pecheurs a bord d'embarcations de peche a forfait s'adaptent a la reglementation. L'effort de peche a bord de navires nolises est demeure uniforme, s'ajustant principalement a la disponibilite de << quelque chose >> a pecher, ce qui indiquerait que leurs clients sont disposes a changer d'especes cibles. Les pecheurs dans des navires de groupe ont pour leur part reagi aux limites de possession de bars noirs (Centropristis striata) et de cardeaux d'ete (Paralichthys dentatus). Comme les pecheurs de navires de groupe sont moins disposes a changer d'especes cibles, il est probable que les exploitants de tels navires sont particulierement vulnerables aux baisses des occasions de peche et du potentiel de prise. [Traduit par la Redaction], Introduction Recreational fisheries management worldwide struggles to limit harvest while concurrently meeting biological and socioeconomic objectives (Cox et al. 2002; Post et al. 2002; Abbott et al. 2018). Fisheries managers [...]

Aim: Physical activity (PA) is a key component for brain health and Reserve, and it is among the main dementia protective factors. However, the neurobiological mechanisms underpinning Reserve are not fully understood. In this regard, a noradrenergic (NA) theory of cognitive reserve (Robertson, 2013) has proposed that the upregulation of NA system might be a key factor for building reserve and resilience to neurodegeneration because of the neuroprotective role of NA across the brain. PA elicits an enhanced catecholamine response, in particular for NA. By increasing physical commitment, a greater amount of NA is synthetised in response to higher oxygen demand. More physically trained individuals show greater capabilities to carry oxygen resulting in greater Vo2max – a measure of oxygen uptake and physical fitness (PF). Methods: We hypothesized that greater Vo2max would be related to greater Locus Coeruleus (LC) MRI signal intensity. In a sample of 41 healthy subjects, we performed Voxel‐Based Morphometry analyses, then repeated for the other neuromodulators as a control procedure (Serotonin, Dopamine and Acetylcholine). Results: As hypothesized, greater Vo2max related to greater LC signal intensity, and weaker associations emerged for the other neuromodulators. Conclusion: This newly established link between Vo2max and LC–NA system offers further understanding of the neurobiology underpinning Reserve in relationship to PA. While this study supports Robertson's theory proposing the upregulation of the NA system as a possible key factor building Reserve, it also provides ground for increasing LC–NA system resilience to neurodegeneration via Vo2max enhancement. [ABSTRACT FROM AUTHOR]

Data from 4,713 fisheries worldwide, representing 78% of global reported fish catch, are analyzed to estimate the status, trends, and benefits of alternative approaches to recovering depleted fisheries. For each fishery, we estimate current biological status and forecast the impacts of contrasting management regimes on catch, profit, and biomass of fish in the sea. We estimate unique recovery targets and trajectories for each fishery, calculate the year-by-year effects of alternative recovery approaches, and model how alternative institutional reforms affect recovery outcomes. Current status is highly heterogeneous-the median fishery is in poor health (overfished, with further overfishing occurring), although 32% of fisheries are in good biological, although not necessarily economic, condition. Our business-as-usual scenario projects further divergence and continued collapse for many of the world's fisheries. Applying sound management reforms to global fisheries in our dataset could generate annual increases exceeding 16 million metric tons (MMT) in catch, $53 billion in profit, and 619 MMT in biomass relative to business as usual. We also find that, with appropriate reforms, recovery can happen quickly, with the median fishery taking under 10 y to reach recovery targets. Our results show that commonsense reforms to fishery management would dramatically improve overall fish abundance while increasing food security and profits.

With growing concerns about global overfishing, market‐based eco‐certification programs like the Marine Stewardship Council (MSC) can incentivise adoption of sustainable practices. Several studies investigated drivers of improvement in market‐driven Fisheries Improvement Projects, but failed to use detailed, standardised measures of progress, or considered small samples. We considered the relative influence market, governance and fishery‐specific drivers have on MSC certification speed and success in 208 fisheries. To evaluate improvement we compared pre‐certification scores from MSC pre‐assessments—rapid high‐level audits against the MSC Standard—to scores from full MSC audits. Drivers considered included measures of pre‐assessment quality, as this initial advice might contribute to later certification success. National fishery management capacity, percentage of MSC catch and landed value were the strongest drivers of successful and rapid certification. Environmental improvements occurred for stock management, ecosystem health and governance aspects. While only 48% of fisheries with favourable pre‐assessment outcomes went on to be certified, improvements in many fisheries with lower pre‐assessment scores were observed in their lead‐up to full assessment. Random forest analyses allowed for considering multiple interacting variables simultaneously and revealed influential drivers under specific fishery contexts. For example, higher certification probability was associated with greater percentage of MSC catch under the full dataset, but not under subsets representing fisheries facing more challenging contexts for certification. Fisheries from lower/middle‐income countries had lower overall probability of certification, but this increased with higher management capacity. This suggests multiple drivers interact in instigating fisheries improvements, and MSC pre‐assessments provide valuable resources to understand this journey. [ABSTRACT FROM AUTHOR]

Although most fisheries assessment and management focuses on the status of individual stocks, and regulations are commonly established as single‐species total allowable catch limits (TACs), much of the catch from global fisheries comes from mixed‐stock fisheries where species cannot be harvested separately. We show that in some fisheries where TAC and catch of demersal fish stocks are tracked, the average fraction of TAC harvested ranges from 21% to 68% overall and is declining. This is, in part, related to efforts to protect all species from overfishing, leading to 'choke species', which limit fishing pressure on other target species. While some choke species arise from a mix of low and high‐productivity species, others result from allocation processes, which can be aggravated by shifting distributions due to climate change. Underutilization of TACs can also result from market limitations, low value of individual species, undercapacity or management measures. Proposed methods for increasing long‐term yield require species to be managed in stock groups, or allowing the abundance of some stocks to fall below target reference points. We suggest that the observed low and declining aggregate harvests are due, primarily, to the focus on single‐stock sustainability measures, rather than performance of the fisheries in relation to potential overall yield. While there is a growing consensus that single‐species management should be replaced by an ecosystem‐based approach, this will require clear legislative directives regarding management of the trade‐offs involved. Time series considered in this analysis do not extend beyond 2019. [ABSTRACT FROM AUTHOR]

We observed large survival differences between wild and hatchery-reared steelhead trout (Oncorhynchus mykiss) during the juvenile downstream migration immediately after release, which persisted through adult life. Following a railway spill of sodium hydroxide into the Cheakamus River, British Columbia, a short-term conservation hatchery rearing program was implemented for steelhead. We used acoustic telemetry and mark-recapture models to estimate survival of wild and (or) hatchery-reared steelhead during 4 years of the smolt migration, with both groups released in 2008. After adjusting for estimated freshwater residualization, 7%-13% of wild smolts and 30%-40% of hatchery smolts died in the first 3 km of the migration. Estimated survival from release to ocean entry was 71%-84% for wild fish and 26%-40% for hatchery fish and to exit from the Strait of Georgia system was 22%-33% for wild fish and 3.5%-6.7% for hatchery fish. A calculated 2.3-fold survival difference established during the downstream migration was similar to that after the return of adult spawners, as return rates were 8.0% for wild fish and 4.1% for hatchery fish. Contrary to current understanding, a large proportion of salmon mortality in the smolt-to-adult period, commonly termed 'marine mortality', may actually occur prior to ocean entry. Nous avons observe de grandes differences sur le plan de la survie entre des truites arc-en-ciel (Oncorhynchus mykiss) sauvages et issues d'ecloseries durant l'avalaison des juveniles immediatement apres le lacher, qui persistaient tout au long de la vie adulte. A la suite d'un deversement ferroviaire d'hydroxyde de sodium dans la riviere Cheakamus (Colombie-Britannique), un programme d'elevage en ecloserie de courte duree a ete mis en aeuvre pour cette espece. Nous avons utilise la telemetrie acoustique et des modeles de marquage-recapture pour estimer la survie des truites arc-en-ciel sauvages et (ou) elevees en ecloserie durant 4 annees de la migration des saumoneaux, les deux groupes ayant ete laches en 2008. Apres ajustement pour tenir compte de la residualisation en eau douce, il a ete etabli que 7-13 % des saumoneaux sauvages et 30-40 % des saumoneaux issus d'ecloseries etaient morts dans les premiers 3 km de la migration. Le taux de survie estime du lacher a l'entree en mer etait de 71-84 % pour les poissons sauvages et de 26-40 % pour les poissons issus d'ecloseries, et a la sortie du reseau du detroit de Georgia, de 22-33 % pour les poissons sauvages et 3,5-6,7 % pour les poissons issus d'ecloseries. Une difference calculee du simple au double (2,3 fois) etablie pour l'avalaison etait semblable a la difference etablie pour le retour des geniteurs adultes, les taux de retour etant de 8,0 % pour les poissons sauvages et de 4,1 % pour les poissons d'ecloserie. Contrairement a la comprehension actuelle, une grande proportion de la mortalite des saumons du stade du saumoneau a celui d'adulte, communement appelee la <>, pourrait en fait se produire avant l'entree en mer. [Traduit par la Redaction], Introduction Early life-history stages of fishes are thought to be critical periods of high and variable mortality that determine recruitment (Hjort 1914), but the temporal resolution of mortality during earlier [...]