Are There Still Plenty of Fish?

A study carried out by Koehn et al . (2017) in the Californian Current found that fishing forage fish resulted in large biomass losses of seabirds and marine mammals. There are clear trade-offs currently occurring between commercial fisheries and conservation objectives. Seabirds in particular are vulnerable to this type of human activity because many of these species are specialist feeders and therefore are highly sensitive to depletion in their prey source. Forage fish therefore have a key role in marine food webs. They represent the main energy pathway through trophic levels that sustains the marine ecosystem.

Why are these tiny fish species so attractive to commercial fishing companies? Forage fish tend to accumulate in large aggregations for breeding. This makes them an easy target for large trawlers as it enables them to catch large landings over a relatively short period and at a low cost. This fast removal of an abundant critical species will lead to a population collapse if fishing rates continue to increase. This will not only cause ecological loss but will also harm the economy as there will not be any more fish to fish. Konar et al . (2019) predicts that forage fish could reach their ecological limit by 2037 if a “business as usual” approach is taken.

What benefits can the human population see from healthy forage fish populations? Ecotourism can bring in high revenue particularly for coastal communities. Predators such as whales and dolphins are highly charismatic animals which people will pay to see through whale watching tours. Konar et al . (2019) estimated ecotourism of this nature can value at millions in regional economies and billions on a global scale. Without forage fish to feed on, there will not be any of these marine mammals left for future generations.

EU Directives such as Habitat and Birds Directive and the Marine Strategy Framework Directive require important habitats such as reefs, coarse sediments, sands and muds to be maintained in good condition. These habitats are predominantly inside the 6nm of the Irish coast. Trawling and dredging are causing physical abrasion to these habitats and disturbance to the species that inhabit them.

References:

Koehn, L.E., Essington, T.E., Marshall, K.N., Sydeman, W.J., Szoboszlai, A.I. and Thayer, J.A. (2017). Trade-offs between forage fish fisheries and their predators in the California Current. ICES Journal of Marine Science , 74(9) , pp.2448-2458.

Konar, M., Qiu, S., Tougher, B., Vause, J., Tlusty, M., Fitzsimmons, K., Barrows, R. and Cao, L. (2019). Illustrating the hidden economic, social and ecological values of global forage fish resources. Resources, Conservation and Recycling , 151 , p.104456.

Marine Institute (2018). Trawl Fishing in Water Inside 6nm around Ireland. Fisheries Ecosystems Advisory Services.