Many very different kinds of fishes reproduce in manners that involve aggregations. Most aggregation based spawning aggregations involve marine fishes, and not only warm-water reef fishes like snapper and grouper but also valuable cold-water fishes such as Atlantic cod. 

Globally, over 200 species of marine fishes, representing over 40 families, reproduce by forming resident or transient spawning aggregations at specific times and locations following Rosemond et al. 2022. Many of the top species in global fisheries aggregate to spawn ranging from pollock,  cod, capelin, Atlantic mackerel, and including pilchard and herring species.

Over 100 reef fish species aggregate to spawn, including many groupers, snappers, porgies, surgeonfish, rabbitfish, parrotfish, mullets and wrasses. Many of the most commercially important species have this reproductive habit, highlighting the need for management to maintain the species and their fisheries.”

Typically no. The breadth of information on spawning, even in better-known species such as snappers and groupers, is still relatively small. However, available information suggests that in most cases, those species that form spawning aggregations are not reproducing in other places and times. 

There are many examples of severe disruption to the populations of species whose spawning aggregations are overfished, a prominent example is the Nassau Grouper, once an abundant fishery species. Uncontrolled fishing of large concentrations of the most fecund individuals in a population can greatly reduce the mature, spawning stock at local and potentially regional scales. 

This can lead to the extirpation of long-standing, once highly productive spawning aggregations. Not surprisingly, killing the maternal “geese that lay the golden eggs” is sustainable for no one.

There are many categories of potential management tools including: catch limits (bag limits), seasonal limits, and spatial limits (MPAs). Many of the best conservation strategies involve multiple layers of protections: combinations of approaches can amplify success in often-changing fisheries.  

Therefore, which approach is better is can be very case-specific. For example a seasonal MPA may protect the aggregation at a certain site but what of the fishing impacts on the migratory paths to the aggregation which are not in the MPA? This is where a seasonal closure can co-amplify the value of a spatial-only management approach. In all cases, establishing trust and buy-in from local fisher communities is foundational to compliance and effective management.