In a reflection on the groundbreaking work of Beverton and Holt in 1957, it becomes evident that the challenges they highlighted regarding the dynamics of exploited fish populations persist today. The latest themed article set, "Advances and challenges in the modelling and assessment of fishery resources," published in ICES Journal of Marine Science, presents novel tools and approaches to address ongoing issues in the field of fisheries management.
The Ongoing Struggle
Decades after the seminal work of Beverton and Holt, accurately estimating critical biological and fishing processes, such as growth, natural mortality, recruitment, and selectivity, remains a challenge. While progress has been made in certain aspects of fisheries modeling and analysis, numerous issues persist. The lack of reliable direct data on vital processes for many species, coupled with the existence of illegal, underreported, and unregulated fishing, complicates the task of assessing the true state of fish stocks.
Modern stock assessment models, classified as data-limited, data-moderate, and data-rich, strive to adapt to the availability of specific kinds of information. However, persistent challenges include the assumption of fixed parameters in the absence of direct data, biased catch and effort data, and the oversight of ecological considerations. The single-species population dynamics approach, upon which current stock evaluations are based, often ignores the intricate interplay of species with environmental variables and trophic relationships.
The latest themed set explores recent advances in various facets of fishery resource assessment and management. The articles aim to shed light on critical issues, including the role of biological processes, the impact of fishing activity, challenges in assessment models, and the integration of ecological considerations.
Highlights from the Themed Article Set
Improving Relative Biomass Indexes
The article by Silva et al. introduces a novel framework for alternative sampling designs in fishery-independent surveys, enhancing accuracy estimates of species biomass. The study focuses on European hake and thorn ray in the Portuguese trawl survey.
Evaluating the Impact of Misreported Landings and Discards
Soto et al.'s sensitivity analysis explores the consequences of underreported scenarios on model estimates, emphasizing the influence of misinformation trends over time.
Assessment of Empirical Harvest Control Rules
Walker et al.'s review challenges the efficacy of trend-based catch rules for small-pelagic species, proposing a constant harvest rate as a more robust alternative, as demonstrated with the case study of sprat in the English Channel.
Life History Parameters for Data-limited Assessment Models
Prince et al.'s meta-analysis presents a database of high-quality growth parameters, providing valuable tools for evaluating data-limited stocks.
Weighting Data Appropriately in Stock Assessment Models
Thorson et al. propose a new self-weighting likelihood for compositional data, the multivariate Tweedie distribution, offering improved performance in assessing population dynamics.
Impact of Environmental Variables on Species Distribution
Lin et al.'s multi-output neural network model explores the correlation between bigeye tuna abundance and environmental factors, providing valuable insights for the management of this commercially important species.
While the themed article set contributes significantly to our understanding of fishery resources assessment and management, it also underscores the existence of critical knowledge gaps. The importance of addressing spatial and ecosystem heterogeneity emerges as a recurring theme, highlighting the need for enhanced integration in stock assessment models. As the fisheries management landscape evolves, these advancements pave the way for more comprehensive and effective strategies in the sustainable exploitation of marine resources.
The main motivators of this themed set are Maria Grazia Pennino (Spanish Institute of Oceanography, Spain) and Marta Coll (Institute of Marine Sciences, Spain).
Read all submitted articles in ICES Journal of Marine Science's latest themed set, Advances and challenges in the modelling and assessment of fishery resources.
Cartoon: Bas Köhler. Click to enlarge.