The paper "When does fishing forage specific affect their predators?" explores the impact of fishing forage species on their marine predators such as birds, marine mammals, and other fish. This new study was led by University of Washington fisheries researcher Ray Hilborn and includes his team of six more respected fisheries scientists.
The study found that there is little evidence for a connection between forage fish abundance and the rate of change in the abundance of their predators, and further states that fishing for forage fish does not have as large of an impact on predator species as previously thought.
A study from 2012 commissioned by the Lenfest Ocean Program had argued that forage fish are twice as valuable when left in the water. However, the new study points to 4 important factors overlooked in their trophic models.
1. The high level of natural variability of forage fish.
2. The weak relationship between forage fish spawning stock size and recruitment and the role of environmental productivity regimes.
3. The size distribution of forage fish, their predators and subsequent size selective predation.
4. The changes in spatial distribution of the forage fish as it influences the reproductive success of predators.
The recommendation for fisheries managers is to consider this issue on a case-by-case basis.
Watch Dr. Ray Hilborn, Dr. Carl Walters, and Dr. Ricardo Amoroso discuss the findings of their new study: