Data Poor Approach for the Assessment of the Main Target Species of Rapido Trawl Fishery in Adriatic Sea

Information on stock status is available only for a few of the species forming the catch assemblage of rapido fishery of the North-central Adriatic Sea (Mediterranean Sea). Species that are caught almost exclusively by this gear, either as target (such as Pectinidae) or accessory catches (such as flatfishes apart from the common sole), remain unassessed mainly due to the lack of data and biological information. Based on cluster analysis, the catch assemblage of this fishery was identified and assessed using CMSY model. The results of this data-poor methodology showed that, among the species analyzed, no one is sustainably exploited. The single-species CMSY results were used as input to an extension of the same model, to test the effect of four different harvest control rule (HCR) scenarios on the entire catch assemblage, through 15-years forecasts. The analysis showed that the percentage of the stocks that will reach Bmsy at the end of the projections will depend on the HCR applied. Forecasts showed that a reduction of 20% of fishing effort may permit to most of the target and accessory species of the rapido trawl fishery in the Adriatic Sea to recover to Bmsy levels within 15 years, also providing a slight increase in the expected catches.

Indirect Impacts of COVID-19 on a Tropical Lobster Fishery’s Harvest Strategy and Supply Chain

The Torres Strait tropical rock lobster Panulirus ornatus (TRL) fishery is of immense social, cultural and economic importance to the region’s Indigenous fishers from both Australia and Papua New Guinea (PNG). During 2020, the COVID-19 pandemic indirectly impacted this fishery as well as a number of other fisheries reliant on international export markets. The TRL fishery is managed using an empirical (data-based) Harvest Control Rule (eHCR) to rapidly provide a recommended biological catch (RBC), based on catch, fishery-independent survey indices and catch-per-unit-effort (CPUE). Here, we summarize the impacts of COVID-19 on each of these critical data inputs and discuss whether the eHCR was considered adequately resilient to this unprecedented disruption to the system. Next, we use a quantitative supply chain index to analyze the impact of disruptions to the supply chain, and inform on potential adaptation strategies. The catch and CPUE data were impacted to varying degrees by external constraints influencing fishing effort, but the fishery-independent survey wasn’t affected and hence there remains an unbroken survey time-series for the fishery extending back to 1989. The eHCR was shown to be reasonably robust because it incorporates longer-term trends over a 5-year period, and accords substantially more weighting (80%) to the fishery-independent survey rather than CPUE data which can be affected by trade and other disruptions. Despite the eHCR not having been tested for scenarios such as a global pandemic, this robustness is a positive given the types of disruptions we will likely face in future climate. The weak links identified in the supply chain were the same as those previously highlighted as sensitive to climate change disruptions. Our supply chain analysis quantifies the impact on system resilience of alternative paths connecting producers to consumers and reinforces that supply chains may be particularly vulnerable to external disruptions if they are not sufficiently diverse.

Comparing a suite of surplus-production-based stock status identification approaches and management procedures

Different approaches have been used to identify fishery stock status when only biomass and catch data are available. However, the performance of the approaches may be affected by the uncertainties derived from different sources (e.g., model misspecification, stock productivity changing, observation error). Here, we propose that the observed biomass associated with the highest calculated surplus production can be used as an indicator (Bhighest_S) to identify stock status. We develop a management procedure (MP) atop a widely used method (i.e., Gcontrol) by incorporating Bhighest_S in the harvest control rule. Two simulations are conducted to compare the stock status identification approaches and corresponding MPs. Using Bhighest_S to identify stock status performs better than surplus production modeling approaches in simulated regime shift scenarios. Compared with the old version of Gcontrol, incorporating Bhighest_S or estimated BMSY in the harvest control rule provides more stable and higher yields. This study contributes to the development and evaluation of indicator-based stock status identification approaches and MPs that only require biomass and catch data.

Optimal shape of the harvest control rule for different fishery management objectives

To determine the optimal shape of the harvest control rule (HCR) achieving common fisheries management objectives (maximizing the average catch, reducing the deviation of yields, and avoiding stock collapse) and ensure robustness to observation errors, we estimate the optimal values of biological reference points (BRPs) composing the HCR. While traditional HCRs usually consist of three BRPs based on the fishing mortality coefficient (F3-HCR), we introduce an alternative HCR defined by 21 BRPs based on the catch levels (C21-HCR) to cover various possible shapes of HCR including smooth ones. We compare the shape and the performance between the optimal C21-HCR and the optimal F3-HCR and conclude that the optimal HCR can be composed of the gradual combination of the basic strategies: the constant escapement strategy, the constant harvest rate (CHR) strategy, and the constant catch strategy. However, the current F3-HCR does not necessarily allow this combination and generally returns lower performance levels than the optimal C21-HCR (since the basic strategy is confined to CHR) excluding the range of low biomass. This result will provide a clear perspective to improve HCR according to the magnitude of assessment errors and to compromise multiple fisheries management objectives when various stakeholders are involved.

Seasonal Losses in Capture Fisheries: Occurrence, Market Responses and Response Constraints

Seasonal losses have challenged capture fishery. Chellenges include difficulty market players to maintain production, and consumers to secure quality fish supply. This paper aims to confirm problems of seasonal fish loss and shows how this links to management. The study, conducted in 2016, followed a case study approach, carried out in seven locations: Palabuhanratu, Blanakan, Probolinggo, Sendangbiru, Pekalongan, Cilacap, and Pati. Interviews were done with fishers, fresh and processed fish traders, processors, consumers, each represented by ten respondents per location. Results show that respondents face problems of seasonal variation and respond with available options. Responses are constrained mainly by financial, facility, and technological factors. I is recommended then that problems and factors be addressed through a harvest control rule schemes. Within these schemes, the rule is described as aiming at (i) imposing harvest levels within the range sufficient to sustain stocks, (ii) avoiding fish deterioration in peak seasons, and (iii) allowing for manageable peak season oversupply to be stored in preparation for low seasons. Complementing to this rule, government interventions are necessary and this can be implemented in concrete actions such as strengthening capital to withstand fluctuations in income, introducing artificial intelligence systems to help market players make decisions.

Evaluating a harvest control rule to improve the sustainability of Japanese fisheries

Fisheries management in Japan is currently at a turning point. MSY based reference points have historically been rejected because of impacts on the fishing industry that would result from their adoption. We propose and evaluate a new harvest control rule (HCR) that uses the biological reference points based on sustainable yield from the stochastic hockey-stick stock recruitment relationship. Management strategy evaluation simulations conditioned on data from Japanese stocks demonstrate that the new HCR avoided recruitment overfishing while providing stable and near maximum catch. The new HCR outperformed Japan’s traditional HCR in terms of conservation, and it outperformed an alternative HCR which is widely used around the world in terms of initial catch reduction and future catch variation. For forecasting and hindcasting simulations, the new HCR showed considerable improvements over traditional HCRs in terms of biomass and catch. This new management procedure can improve the current and future status of many overfished stocks in Japan as well as increase economic efficiency and better protect ecosystems.

Management strategies for spasmodic stocks: a Canadian Atlantic redfish fishery case study

There exist few recommendations for managing stocks with spasmodic recruitment, despite such stocks being not uncommon. Management procedures (MPs), developed for two species of redfish (Sebastes mentella and Sebastes fasciatus) in eastern Canada, are recommended for setting catch limits during periods of high and low abundance. A well-designed fishery-independent trawl survey is essential to provide advance warning of strong recruitment events and project future recruitment. Under an “inventory management” strategy, a more appropriate aim in spasmodic stocks may be to maximize the number of years with “good catches,” instead of maximizing total catches, as is traditionally considered in management strategy evaluation (MSE). Following a spasmodic recruitment event, an empirical harvest control rule based on larger fish delays the harvest of large cohorts by a few years, targets more commercially valuable fish sizes, and reduces the risk of growth overfishing. Capped MPs produced longer periods of large catches than uncapped MPs. MPs allowed for low harvests during periods of low abundance, thus avoiding unnecessary hardship in the industry. MPs evaluated here could be good candidates for other stocks with similar or less extreme recruitment variability.

Sixty-five years of northern anchovy population studies in the southern California Current: a review and suggestion for sensible management

The central stock of northern anchovy (CSNA; Engraulis mordax), the most abundant small pelagic fish in the southern California Current, is key to ecosystem functions. We review drivers of its population dynamics in relation to management. Springtime upwelling intensity lagged by 2 years co-varied positively with CSNA biomass, as did the abundance of Pacific sardine (Sardinops sagax; weakly negative). CSNA population dynamics indicate the need for a multi-species stock assessment, but given serious challenges with modelling population collapse and recovery dynamics, and its moderate fisheries, we suggest that sensible management could be a simple 2-tier harvest control rule designed to emphasize the key trophic role of CSNA in the ecosystem while maintaining moderate socio-economic services. We recommend a monitoring fishery of no more than 5 KMT year−1 split between central and southern California when the stock falls below the long-term median abundance estimate of 380 KMT across the California portion of its range, and a catch limit of 25 KMT year−1 when the stock is above this reference point. This rule would be precautionary, serving to maintain the most important small pelagic forage in the ecosystem, various fisheries interests, and information streams when the population is in a collapsed state.

Integration of bioenergetics in an individual-based model to hindcast anchovy dynamics in the Bay of Biscay

The population of European anchovy of the Bay of Biscay collapsed at the beginning of the 21st century, causing the closure of its fishery between 2005 and 2010. In order to study both the human and environmental causes of the anchovy population dynamics, an approach coupling individual bioenergetics to an individual-based model was applied between 2000 and 2015. This modelling framework was forced with outputs from a physical–biogeochemical model. In addition to a base-case scenario with realistic forcing, alternative scenarios were run without inter-annual variability in either fishing mortality or environmental conditions. During the decrease in population biomass, a high fishing pressure coincided with a combination of environmental variables promoting the appearance of large individuals that could not survive severe winters because of their high energetic demands. The recovery of the population was favoured by a period of warm years with abundant food favouring the winter survival of age 1 individuals, in coincidence with the closure of the fishery. Our modelling approach also allows to test the consequences of a retrospective implementation of the current harvest control rule from 2000 which, according to our results, would have prevented the collapse of the population and avoided the fishery closure.