Title : By removing high performance aerobic scope phenotypes, capture fisheries may reduce the resilience of fished populations to thermal variability and compromise their persistence into the Anthropocene
For the persistence of fished populations in the Anthropocene, it is critical to predict how fished populations will respond to the coupled threats of exploitation and climate change for adaptive management. The resilience of fished populations will depend on their capacity for physiological plasticity and acclimatization in response to environmental shifts. However, there is evidence for the selection of physiological traits by capture fisheries. Hence, fish populations may have a limited scope for the rapid expansion of their tolerance ranges or physiological adaptation under fishing pressures. To determine the physiological vulnerability of fished populations in the Anthropocene, metabolic performance was compared between a fished and spatially protected Chrysoblephus laticeps population in response to thermal variability. Individual aerobic scope phenotypes were quantified using intermittent flow respirometry by comparing changes in energy expenditure of each individual at ecologically relevant temperatures, mimicking variability experienced as a result of upwelling and downwelling events. The proportion of high and low performance individuals were compared between the fished and spatially protected population. The fished population had limited aerobic scope phenotype diversity and fewer high performance phenotypes, resulting in a significantly lower aerobic scope curve across low (10 °C) and high (22 °C) thermal treatments. The performance of fished populations may be compromised with predicted future increases in cold upwelling events. This requires the conservation of the physiologically fittest individuals in spatially protected areas, which can recruit into nearby fished areas, as a climate resilience tool.
What will audience learn from your presentation?
- The information obtained from this study will provide much-needed insights into the link between fish behaviour and physiology and improve our understanding of the adaptive capacity of important coastal fishery species to the ever-increasing impacts of human-induced global change.
- We highlight future research areas required to fully understand how physiology is influenced by the selective processes driven by fisheries. For example, long-term monitoring of the physiological and behavioural structure of fished populations, their fitness and catch rates are required.
- We discuss how information on the phenotypic traits of individuals can be used to conserve the physiologically and behaviourally fittest individuals and allow them to reproduce. Behavioural and physiological-based management approaches will assist in conserving coastal fish populations, and in this way preserving human food security and the livelihoods of coastal settlements.
- Policy makers will be provided with access to collected data, as well as prompted for future research collaborations. We present the need for policy intervention to alter harvest strategies to protect phenotypes that are most vulnerable to fisheries selection. We also encourage the protection of vulnerable phenotypes in Marine Protected Areas that supply fished areas. We encourage conservation through local fishing communities that rely on fishing as a primary source of income. In this way, local households can earn an income, as well as partake in protecting their coastal environments.