Lack of data makes it difficult to assess how invertebrates are affected by fishing

Marine invertebrates such as starfish, shrimp, and Norwegian lobster are important for the structure and function of the ecosystem. In the study, the researchers evaluated the potential effects of west coast fishing on 93 species of invertebrates. The study includes both species that are directly targeted by the fishery, such as shrimp and Norwegian lobsters, and by-catch, such as sea urchins and crabs.

“The species can be affected in different ways. They can be caught and thrown back into the sea and they can be physically affected by the fishing gear, but fishing can also lead to changes in the food web that indirectly affects the animals”, says Linnea Morgan, lead author of the study and environmental analyst at the Institute of Marine Research at SLU.

Lack of data in more than half of the evaluated species

By combining a range of biological attributes (e.g. maximum age, maximum length, and age at sexual maturity) with attributes that characterize west coast fisheries (e.g. fishing depth and mesh size), Linnea Morgan and her colleagues have calculated and assigned a risk level for each of the 93 animal species. 56% were classified as data deficient for the attributes needed to calculate risk level. In addition, data deficiency was more prevalent for many of the species classified as high risk.

"Ecological risk assessments are central to the ecosystem-based fisheries management that everyone is now striving for. To understand the effects of fishing on invertebrates, we need better data, and we can partly achieve this by developing the sampling programs we have today," says Linnea Morgan.

For the future; developed data collection

Currently, much of the data collection occurs via onboard observer programs, where observers are on board commercial fishing vessels. However, sampling procedures and protocols for non-commercial invertebrates are not as stringent as those used for fish. The quality of the sampling is also affected by how much time and species knowledge the observer has.

“I really hope that this study can help inform management decisions for invertebrates as well as drive research to fill the data gaps that we’ve highlighted. Especially since fishing for invertebrate species such as shrimp and octopus is becoming more common," says Linnea Morgan.

Read the full article Ecological risk assessment of invertebrates caught in Swedish west-coast fisheries in Fisheries Research.