An exciting new publication just came out helping us better understand Nassau grouper populations in The Bahamas (article here). Using acoustic telemetry data, Dr. Craig Dahlgren and others recorded the movements of different sized Nassau grouper to examine when and where individuals would migrate to spawning aggregations. They found that individuals did not migrate to aggregation sites until they were 54 cm in total body length, suggesting a new and increased minimum size limit for fishing regulations on Nassau grouper. To illustrate, current Bahamian regulation permits a minimum catch size of 3 lbs (1.36 kg), which in our own work on Nassau grouper, we have found individuals to weigh over this amount at 43 cm, ~10 cm less than their potential size of maturation. Furthermore, their movement data also suggests that individuals migrating for the first time were slower than ‘seasoned’ individuals but their swimming speeds were similar on their return home suggesting migration movement behaviors may be learned.
As many of you probably know from our previous posts (see here), Nassau grouper populations throughout the Caribbean have severely suffered from targeted fishing on their spawning aggregations sites. Of the 50 recorded spawning aggregations known, 32 or more are now considered to be commercially extinct. With individuals traveling from five to hundreds of kilometers to spawn, the loss of an entire spawning site paints the picture for how far-reaching such fishing practices can have on entire species populations. Research actively testing the efficacy of current and future fishing regulations and management strategies, such as this paper, are absolutely necessary to keep our valuable marine ecosystems and their species resilient.