Daniel Pauly

Life history strategies such as rapid growth and high population turnover rates observed in vertebrates have been thought to have emerged relatively late in evolution. However, very little direct evidence exists at the species level for early vertebrates. In this study, a large fossil collection of over 450 specimens of Protaspis spp, heterostracan agnathans from the Cottonwood Canyon Formation at Beartooth Butte, Wyoming, from the Early Devonian, was analyzed. Morphological observations, analysis of bone plate completeness, and length-frequency analyses using ELEFAN—commonly used in recent fish studies—were applied to reconstruct growth rates, cohort structure, and ontogenetic processes. Protaspis specimens exhibited a continuous growth series from juvenile to adult stages, and a clear cohort structure was identified from the length-frequency distributions. The ELEFAN analysis suggested a life-history characterized by rapid growth and a short life span, and these features remained consistent in subset analyses restricted by species or locality, confirming the robustness of the estimates. Furthermore, the integration of the dermal bone plates progressed during the late stages of ontogeny, revealing that the rapid growth during the juvenile stage preceded the completion of this defensive structure. Comparisons of their growth parameters with those of extant fishes show that Protaspis does not align with slow-growing, long-lived “living fossil” taxa, but instead clusters with small-bodied, fast-growing species. These findings suggest that life-history strategies involving rapid growth and high population turnover were already established in early jawless vertebrates, much earlier than previously assumed.

Rising ocean temperature alters fish growth and mortality, but its effects on the length-frequency distribution of fish populations remains poorly understood. Here, we use an equilibrium age-structured fish growth model to simulate population length-frequency distributions under various combinations of the von Bertalanffy growth parameter ( K ) and mortality ( M ) rates, to investigate how widely expected temperature-driven reductions in asymptotic length ( L _inf ) may affect mean and maximum lengths in a population. We show that substantial variation in mean length (up to 40%) can occur under empirically observed M / K ratios, with no change in L _inf . We also find that mean length can increase by up to 25% despite a 10% reduction in L _inf . This only occurs if M decreases or K increases such that population M / K ratios decline by 25-50% across spatially separate populations experiencing different temperature conditions. However, whether such a reduction in the M / K ratio in a population is realistic under climate-driven temporal warming remains uncertain. Length-frequency distributions are a key driver of trophic and non-trophic interactions in aquatic communities and are core indicators of exploitation status in fisheries management. Anticipating their responses under future climate scenarios is therefore critical to assess human impacts and to manage fisheries sustainably.

The oxygen consumption of adult fish (Q) is proportional to their body weight (W) raised to a power, estimated as the slope (d_Q) of a linear regression of log(Q) vs. log(W). Similarly, the gill surface area of adult fish (GSA) is proportional to W raised to the power d_G, as also estimated via a log-log linear proportional to their surface area. Moreover, because of Fick’s laws of diffusion, d_Q should be at least similar to d_G. Recently, the claim has been made that non-zero differences between d_Q and d_G invalidate the Gill-Oxygen Limitation Theory (GOLT), which suggests that the O₂ supplied by gills growing with d_G d_G and d_Q in 33 fish species and other information that (i) while individual differences between d_Q and d_G are observed in several cases, there is no significant overall difference across the 33 estimates and (ii) large differences between d_Q and d_G are primarily due to ontogenetic changes in scaling (OCS), likely ontogenetic changes in gills’ water–blood (or ‘diffusion’) distance and, as well, multiple sources of experimental variability and potential errors, leading to outliers and random differences.

Fishmeal and fish oil (FMFO) are critical inputs for the compound aquatic feeds sustaining the fed aquaculture sector, yet there is limited publicly available information on the location of FMFO production factories around the globe. This makes it difficult to assess the environmental, social, and economic impacts of individual factories and the industry’s footprint as a whole. To fill this knowledge gap, we compiled location data for FMFO factories across 63 producing countries. We identified 506 factories owned and/or operated by 413 companies. We provide an open-source database that includes FMFO factory locations, company names, and raw material types. This study offers a first look at the spatial distribution of the FMFO industry and serves as a valuable resource for marine resource managers and policymakers. Knowing the locations of factories and where FMFO production is concentrated can inform the development of cooperative national and international policies to ensure environmentally and socially responsible standards.

Analysis of length-frequency data using the ELEFAN (Electronic Length-Frequency Analysis) approach and software is widely used to quantify the growth, mortality, longevity, and related parameters of Recent marine animals. Here we analyze a sample ( n = 211) of the Ediacaran metazoan Parvancorina minchami Glaessner, 1958, from the Vendian siliciclastic marine deposits of the southeastern White Sea region, Russia. The results fit a von Bertalanffy equation with the parameters L _∞ = 2 cm, K = yr ⁻¹ (with t ₀ not estimated) and an instantaneous rate of mortality ( M ) of 1.44 yr ⁻¹ , implying M / K ≈ 2, as commonly occurs in Recent small invertebrates. These parameter values also imply a longevity for P. minchami of about 4 yr. The concepts and approach used here, previously applied to an Ordovician trilobite and a Cambrian radiodont, suggest that inferences on growth, mortality, longevity, and related parameters can be obtained from suitable size-frequency samples of long-extinct metazoans, opening new vistas on their growth dynamics and functional roles in ancient ecosystems.

Marine fisheries are crucial to the economy, livelihood, food security and culture of coastal nations and communities, significantly contributing to the United Nations Sustainable Development Goals. A decade ago, T. J. Pitcher and W. W. L. Cheung highlighted the dichotomy in the perception of fisheries' status, concluding that long‐term sustainability and benefits to people were threatened by overexploitation, climate change, pollution, habitat change and other human stressors. They advocated for a fundamental shift towards ecosystem‐based management, better enforcement of existing regulations and more inclusive and equitable management practices. In this paper, we provide an updated review of the status of global fisheries, reflecting on policy actions, key assessments and research findings over the past decade. While there is a growing recognition of the need for sustainable fisheries management and ocean protection, the overall status of fisheries has not improved. Despite progress in international and national policies addressing direct and indirect drivers such as climate change and harmful practices, these trends have not been reversed. Many challenges identified by Pitcher and Cheung and others persist. Additionally, new and emerging issues such as deep‐sea mining, plastic pollution, unhealthy aquaculture development, increasing social inequity and the rapidly increasing push for the acceleration of the blue economy exacerbate the complexity of achieving fisheries and other ocean management goals. Debating whether there is more hope or despair in global fisheries has become irrelevant. Pathways to ‘bend the curve’ for fisheries are clear, and effective actions are now urgently needed to achieve desirable and sustainable fisheries.

Mechanistic explanations of the impact of climate change on fish growth are currently under debate. However, critical assessments of even the most prominent theories are not always based on accurate interpretations of their underlying mechanistic models. This contribution addresses some of the major misunderstandings still causing the Gill-Oxygen Limitation Theory (GOLT) from being examined based on its actual structuring elements and assumptions, rather than erroneous perceptions. As we argue, recent critiques of the GOLT are based on implausible interpretations of respirometry data that are invoked to distinguish maintenance costs and overhead costs of growth. Discussing the current state of the debate, we emphasize the fact that fasting young and, thus, growing fish for short periods of time is not sufficient to suppress energy (i.e., oxygen) allocation to growth. In the process of dealing with these issues, several cases of apparent ‘counter-evidence’ are discussed. Highlighting the need to base critical discussions and examinations of the GOLT on its actual predictions, we recommend that testing the theory should focus on broad reviews or meta-analyses, e.g., on datasets of gill surface area and the relationship of these data to growth performance under different temperature regimes.

Aquacultured carnivorous species consume most of the world’s fishmeal and fish oil (FMFO), which itself is primarily derived from small pelagic fish. This has raised concerns about the practice’s impact on wild fish stocks, ecosystems, and coastal communities that rely on these fish. The aquaculture industry claims a decreasing dependence on wild fish, relying on the Fish In:Fish Out (FIFO) metric as a ratio of the quantity of wild fish required for farmed fish production. This is misleading because it usually assumes constant FM or FO yields, inclusion rates and feed conversion ratios, which vary widely. Thus, a constant FIFO value for a given species cannot be assumed. Furthermore, low FIFO values resulting from averaging carnivores and herbivores conceal the high feed requirements of carnivore species. The increasing use of FMFO from by-products does not demonstrate a decreased use of wild fish but rather reflects a growing demand for FMFO, particularly for the fast growing and valuable salmon and shrimp farming industries.