Predation of fish eggs and larvae
Project background
Several stocks of marine round-fish of economic relevance to the U.K. are currently in poor condition. Of particular concern is the status of the Irish and North Sea cod and North Sea plaice. Under the reformed Common Fisheries Policy, stocks being fished unsustainably must be managed by recovery plans. These plans seek to attain a rapid (within 5 years) re-building of the spawning stock biomass to a level where the population is considered to be viable.
Project benefits
This project addresses a key issue in stock sustainability that is currently poorly understood and tends to be ignored in standard fisheries models. There is a large range of potential predators responsible for egg and larval mortality for example amphipods and mysids, gelatinous predators and fish. For many of these groups there is limited data on their distribution and abundance.
The project will give us the tools needed to study how predators interact with the early life history stages of commercially important species. The field studies will provide new estimates of predator abundance, distribution and spatial and temporal overlap with fish eggs and larvae in the Irish and North Seas. Field studies may also identify important predators and behaviors which have been previously overlooked.
As well as being of scientific interest, the results will support the provision of policy advice to Defra on recovery plans and long-term sustainability of stocks under fisheries scenarios and climate change.
Project objectives
Cefas, in partnership with the University of East Anglia, will deliver the following objectives:
- Modify existing TaqMan probes for cod, haddock and whiting and demonstrate their specificity is retained against other potential prey items
- Develop a DNA-based probe for plaice and demonstrate its specificity against other potential prey items
- Determine the effects of digestion on reliability of detecting presence of target prey in predators stomachs and intestines
- Develop particle tracking individual-based models
- Undertake field studies, including acoustic surveys, on predation of eggs and larvae in the Irish and North Sea
