Over or Under? Skate and Ray Fishing

Jurgen Batsleer, Christopher A Griffiths, Katinka Bleeker, Graham Johnston, Massimiliano Cardinale, Pascal Lorance, Comparisons of landings to scientific advice indicate overshooting within the common TAC for skates and rays in the Northeast Atlantic, ICES Journal of Marine Science, Volume 81, Issue 3, April 2024, Pages 470–479,

Fishing Limits

Total allowable catch (TAC) is a set limit of how many fish of a stock can be caught. A stock is a population of a fish species that is taken from for economic or recreational use in a particular region. TAC is set by the International Council for the Exploration of the Sea (ICES) and can be stock specific or for a collection of stocks called a common TAC. In concept the common TAC is scalable to each species in the group. In other words, the most abundant fish would make up the majority of the catch, followed by the second most abundant, then the third, and so on. This is not the case in practice.

The skate and ray common TAC was assessed in the Northeast Atlantic to see if the concept was working as intended. This common TAC includes 26 stocks, 8 species, and 3 ecoregions. Skates and rays are of special interest because of their vulnerability to overfishing. This is due to their slow growth rates, late maturity, and low reproduction levels that make recovery difficult.

Skates and rays of the Northeast Atlantic. A: Blonde ray (Raja brachyura), B: Cuckoo ray (Leucoraja naevus), C: Thornback ray (Raja clavata), D: Spotted ray (Raja montagui). (Original photos)

Catching up on Landings

Researchers found a variety of landing results that both overshot and undershot recommended landing limits for skate and ray species. Overall, blonde ray was the most exploited with landings double the recommended amount. Cuckoo and spotted rays were also overfished in certain ecoregions creating concern for these stocks. On the flip side, thornback ray was consistently under-caught across all three ecoregions. Thornback ray is the most common skate in the Northeast Atlantic, meaning it should make up the bulk of the catches. However, this is not the case in practice, leading to the consistent undershooting of recommended landings.

Landings for skate and ray species of the Northeast Atlantic for each stock in the three ecoregions from 2016 to 2022. The left column is the relative catch difference from ICES landing advice. The right column is the absolute difference in tonnes. The white section indicates undershooting of ICES landing advice while the gray section indicates overshooting. (Batsleer, et al. 2024)

Unequal Catches

If the blonde ray is not as common as the thornback ray, how is it landed more consistently, leading to this overfished status? It may be because the blonde ray is one of the most valuable skates in the region. It is one of the largest species in the area, and has the highest price per kilogram on the market. It simply is more bang for your buck to land more blonde rays versus thornback rays. As for cuckoo and spotted rays, it may be more happenstance that they congregate in the areas that are heavily targeted by fishers.

This study demonstrates a need for more stock specific total allowable catch limits in the Northeast Atlantic. Skate and ray species are each distinct in their population numbers and vulnerability to overfishing. Creating stock specific TAC will help regulate landing limits more consistently. Not only will this reduce the pressure on blonde ray populations, but also increase thornback ray landings, reducing the impact of this shift on the local economy. Future work should continue to monitor this fishery and provide stock specific information to make more detailed TACs.

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