(Eleuthera, Bahamas) – As we have discussed in past editions of Conservation Corner, queen conch are an incredibly valuable resource to the people of The Bahamas. Research throughout the Caribbean, and in other family islands, has shown that conch numbers keep decreasing. Research done by the Sustainable Fisheries team at the Cape Eleuthera Institute this past summer shows the same situation is happening in Eleuthera.
Nursery grounds for conch are usually shallow water and near shore, and generally act as a refuge for juvenile conch to grow up and mature. Historically, South Eleuthera has been home to numerous nursery grounds, including the largest surveyed nursery in The Bahamas, near the Schooner Cays.
CEI’s Sustainable Fisheries team performed snorkel surveys this past summer to assess the densities in these nursery grounds. They also re-surveyed the Schooner Cays, an area once surveyed in 1993. What they found was alarming. Numbers in each of these nursery grounds were low, below the threshold for even being considered a nursery ground anymore. And the numbers at the Schooner Cays were also much, much lower than they were 20 years ago. Reasons for this could include seasonal movements of nursery grounds (although undocumented at those locations), but recent surveys of middens (piles of discarded conch shells) show that more than 40% of conch harvested and knocked near shore in South Eleuthera are juvenile. This means that those individuals haven’t reproduced, and haven’t contributed to future generations. This helps to explain the decline in the near shore nursery grounds- many of those conch have been fished!
(LEFT) A juvenile conch found in the seagrass during a nursery ground survey. (RIGHT) An adult conch next to an egg mass, a positive sign of local reproduction.
The team also had the opportunity to survey conch mating grounds this summer, again replicating previous surveys from 1993. This entailed SCUBA diving in different depth zones, looking for spawning aggregations, or large groups of adult conch looking to mate. Conch have density dependent reproduction, meaning that once their numbers get too low, even if there are still conch out there, they won’t get the chance to meet up and mate. The peak of conch mating season is the warm summer months, so surveys were performed in June and July.
Preliminary analysis of this data is also dismal- numbers are significantly lower than densities of conch seen 20 years ago (see Figure 1). The team surveyed a much greater area, to see if the conch were aggregating in a different spot, but weren’t able to find the numbers seen in the past, suggesting that the decrease isn’t due to conch simply moving to a different location. What is more likely is that constant fishing pressure is removing individuals from the population at a rate faster than new conch are being added.
But, there is some good news. While diving, the team was able to identify a few mating pairs of conch, and they even found a conch egg mass! That is a positive sign of reproduction still occurring in these waters. Whereas in the 1990’s conch were forming groups in the hundreds, today we were lucky to see a group of 40.
While we see conch mating, the numbers are continuing to decline. There are conch still in our waters, but the numbers continue to go down every year. In other places like Mexico, Belize, Haiti, and Florida, there have been total collapses of the fishery, due to overfishing to the point of no reproduction and no new juveniles. But, because there are still some conch left in The Bahamas, this means that we DO have a chance to protect our conch fishery, but that action has to be taken NOW to guarantee conch in the future!
What YOU can do:
- Do not harvest or consume juvenile conch
- Do not harvest conch with lips less than 15 mm (about the thickness of a new Bahamian penny)
- Try to eat more sustainable foods like snapper or lionfish
- Support the national Conchservation campaign (www.facebook.com/conchservation)
- Support initiatives aimed at protecting/increasing the conch fishery, such as a closed season
For more information on queen conch research at CEI, please contact Claire Thomas at firstname.lastname@example.org, or call 334-8552 ex. 6206.