Fishery Management and Spawning Aggregations

Background

Many reef fishes, such as groupers, parrotfish, wrasses, snappers, and surgeonfishes, form spawning aggregations. A spawning aggregation occurs when a large number of fish come together temporarily at specific sites to reproduce. There are two main types of spawning aggregations:

1. Resident aggregations – Fish tend to live near the aggregation site and only have to travel a short distance to get to the site. Resident aggregations form on a regular basis and tend to be formed by smaller fishes such as wrasses.
   
2. Transient aggregations – Fish travel long distances to aggregation sites.

Spawning aggregations tend to form at specific sites to which fish migrate year after year; however, there is evidence that specific sites may vary for some species. Additionally, many different species may use the same site concurrently or at different times of the year. Spawning aggregations may be the primary source of larvae that replenish local fishery populations.

Since spawning aggregations tend to be predictable in location and time, they are highly susceptible to overfishing. Fishermen are able to catch a large number of fish in a short time. Intense fishing on these aggregations can result in the disappearance of aggregations all together. The decline in spawning aggregations ultimately results in the reduction of the population because fewer and fewer fish are reproducing each year.

What is NOAA Fisheries Service doing?

NOAA Fisheries Service has been working with state, territory and academic partners to understand the status of spawning aggregations in U.S. waters, to increase our knowledge about the life history and habitat requirements of commercially important aggregating species, and to assess the impact of management activities.

In the Atlantic Caribbean, spawning aggregation work funded through the NOAA Coral Reef Conservation Program has focused on:

1. Assessing the effectiveness of marine protected areas in aiding in the recovery of spawning aggregating species such as snappers and groupers. There is preliminary evidence that a few selected species are more abundant in Tortugas Ecological Reserve.
   
   
2. Surveying Red Hind (Epinephelus guitatus) biomass in Puerto Rico using hydroacoustics. Researchers used four spiltbeam echo sounders to survey the entire coastline of Puerto Rico. Fish aggregations were prevalent in some areas, but sparse in others.
   
   
3. Identifying and assessing grouper and snapper breeding aggregations and spawning habitat in the U.S. Virgin Islands. NOAA Fisheries Service made a temporary ruling to close a known yellowfin grouper spawning aggregation area to fishermen from February 1 to April 30 this year (2005). This site is also used to support nassau grouper; the nassau grouper fishery in federal waters has been closed since the 1990’s because of commercial extinction. Nassau groupers are routinely caught as bycatch in the yellowfin grouper fishery. To preserve this spawning aggregation site with the hopes that protection will also enhance thegrouper population in the Virgin Islands, scientists and managers needed to act quickly. Based on documented scientific data, Dr. Richard Nemeth requested action from the Southeast Regional Office and the Caribbean Fisheries Management Council to close Grammanik Bank to fishing.
   
   
4. Conducting research in selected marine reserves of the Meso-American reef and the Dry Tortugas ecosystems to understand the recruitment connectivity between these two regions. Researchers will examine the trace element composition of fish otoliths to assess the relationship between local recruitment and in-flux of larvae from distant spawning aggregations.
   
   
5. Monitoring and mapping of Gulf of Mexico MPA's. Through contracts with U.S. Geological Survey and the Univeristy of Florida, high resolution mulitbeam maps of Mandison Swanson and Steamboat Lumps marine protected areas have been produced. These maps have aided in the monitoring of fish assessmblages and the evaluation of the effectiveness of these two MPA's as a management tool to protect spawning aggregations of gag grouper (Mycteroperca microlepis). Additional information.
   

In the Pacific, spawning aggregation work has been mainly funded through the General Coral Reef Conservation Grant Program. These projects support fishery management needs and assess fish movement to and from aggregation sites and susceptibility to fishing pressure while migrating.

Return to the NMFS coral reef fisheries management page.