A study from marine researchers claim that a study of theirs demonstrates the link between climate change and cod in the North Sea
A recently released study from four leading marine researchers claim that a study of theirs demonstrates the link between climate change and cod in the North Sea.
Entitled, “Addressing the dichotomy of fishing and climate in fisheries management with the FishClim model”, the was study carried out by Grégory Beaugrand, Alexis Balembois, Loïck Kléparski and Richard R. Kirby, and it claims to demonstrate the enormous impact of climate change on cod populations in the North Sea.
The abstract to the study says:
The relative influence of fishing and climate-induced environmental change (CIEC) on long-term fluctuations in exploited fish stocks has been controversial because separating their contributions is difficult for two reasons. Firstly, in general there is no estimate of the CIEC for a period prior to fishing and, secondly, the assessment of the effects of fishing on the stocks has been carried out at the same time as the CIEC. A study describes a new model that has been called FishClim and that is applied to North Sea cod from 1963 to 2019 to estimate how fishing and CIEC interact and how both may affect stocks in the future (2020-2100) using CMIP65 scenarios.
The FishClim model shows that both fishing and CIEC are interrelated and can act synergistically (for example, the 2000-2007 collapse) or antagonistically (for example, the second phase of the gadoid burst). Failure to follow IECS, for fisheries management to immediately adjust fishing effort in response to environmentally driven changes in stock productivity, will therefore create a detrimental response lag that may lead to stock collapse. of the population.
We found that during 1963-2019, although the effect of the drivers of fishing and CIEC fluctuated annually, the joint influence of fishing and CIEC on the North Sea cod stock was almost equal, with ~55 and ~45%, respectively. Consequently, the application of FishClim, which accurately quantifies the respective influence of fishing and climate, will help to develop better strategies for long-term and sustainable management of fish stocks.
Managing fish stocks has always been a difficult task because stocks exist in complex ecosystems that can undergo substantial change triggered by extrinsic forces (for example, fishing and IECS, see IECS definition in Table 1) and intrinsic (e.g. biological or ecological processes) These changes can lead to population collapses due to overexploitation or climate-induced spatial range alterations, with consequences on local fish abundance Although many studies have investigated how the fisheries and the environment can interact to affect a fish population, the precise and respective contribution of fisheries and IECS and how it varies over time remains poorly understood, although this knowledge is likely to be critical to effective fisheries management.
The Atlantic cod Gadus morhua L. has declined in the North Sea since the end of the gadoid burst and it has been debated whether or not the IECS has contributed overfishing to the decline in spawning biomass (SSB). Surprisingly, although some studies have jointly investigated the influence of CIEC and fishing on cod SSB, no attempt has been made to precisely quantify the effects of both factors, despite their importance in terms of stock management. As a result, current management practices continue to ignore the potential influence of CIEC on cod stocks.
To investigate the influence of fishing and IECS and how they might interact to affect the North Sea cod population, they designed a model in which the size of the cod population (Standardized Spawning Stock Biomass or dSSB in further, depended on (i) the population growth rate r, (ii) the fishing intensity α and (iii) the maximum standardized SSB (referred to as mdSSB hereafter) that can be reached in space and time and that can only result from the CIEC in the absence of exploitation (‘Methods’).We have called this model FishClim and applied it to the North East Atlantic (seas surrounding the UK) with a spatial resolution of 0.25° latitude × 0 .25° longitude, emphasizing the North Sea cod stock.