Grand Bahama Acoustic Tracking Study Summary

Introduction

Throughout the islands of The Bahamas, bonefishing is not only a popular sport, but also an important component of the tourism industry that contributes greatly to the economic health of many communities. For such a valuable fishery, surprisingly little is known about bonefish movements, particularly when it comes to migrations associated with their reproduction.

Although bonefish pre-spawning aggregations have been documented near deepwater drop-offs along the coastlines of Eleuthera, Abaco, and Andros, only anecdotal information exists for the island of Grand Bahama. Although bonefishing guides have noted that large schools of bonefish occur on the south side of the island during the winter months, it is unclear where these bonefish originate. Historically, at least some of the large bonefish populations on the north side of the island were reported to have used Hawksbill Creek to move to the south side. While building the port in the 1950s and 1960s, however, Hawksbill Creek was blocked by the construction of a causeway.  Since then, however, the man-made Grand Lucayan Waterway (GLW), a canal that now bisects the entire island, provides a way for bonefish to traverse the island…but, the question is: Do they use it?

The Study

The specific objectives of this project were:

1. To assess if bonefish use the GLW to traverse the island and/or if they swim around the East or West ends of Grand Bahama to get to the spawning grounds, and
2. To identify the location(s) of pre-spawning aggregations of bonefish on Grand Bahama.

Before the spawning season, the team deployed VEMCO acoustic receivers in strategic locations around the entire island, including 32 receivers provided by the Ocean Tracking Network, for a total of 67 VEMCO acoustic receivers in the final array. These additional receivers greatly increased our ability to track bonefish, and all of our telemetry data will be added to the Ocean Tracking Network’s global database.

A total of 56 bonefish were implanted with acoustic tags in locations all around Grand Bahama. Once released, these acoustic tags allow us to track the movements of these bonefish to their spawning sites.

What Did We Find Out?

The results of the first year of the study revealed that some of the fish tagged on the North side did indeed use the Grand Lucayan Waterway as a movement corridor for migrations during spawning season. Others went around both the east and west ends of the island. This data also confirmed that bonefish are forming pre-spawning aggregations only on the south side of Grand Bahama.

In year two, which focused on pinpointing the locations of pre-spawning aggregations and has now been completed, early data analysis has revealed that there are only three pre-spawning aggregation sites on Grand Bahama, with multiple bonefish going there to spawn on multiple days during the study (late October 2014–early June 2015).

Some of the interesting findings were:

1. Bonefish continued both to use the Grand Lucayan Waterway as a corridor to reach spawning locations, as well as to swim around both ends of the island.
2. The longest round trip migration was one of at least 180 miles from north of Dover Sound all the way to the south side of the island around East End.
3. Several fish spawned at least five times during the study.
4. Two fish used multiple pre-spawning aggregation sites.

With only three pre-spawning sites on the island, commercial development or illegal fishing in any one of these three areas could destroy a local fishery. These findings emphasize that protecting critical habitats are essential to keeping the multi-million-dollar bonefish fishery healthy for years to come.

It Takes a Village

There are a lot of behind the scenes efforts and coordination needed for such a large project to succeed, and this project would not have been possible without the extraordinary support and personal assistance from Jason Franklin and Greg Vincent of H2O Bonefishing, as well as Paul Adams and the bonefishing guides at North Riding Point Club. They provided both excellent advice and support, including boats, guides, lodging, and refreshments, which is no small feat for a project of this size.

We would also like to recognize the members of our science team: Dr. Karen Murchie (College of the Bahamas); Dr. David Philipp and Julie Claussen (FCF); Dr. Aaron Adams and Justin Lewis (Bonefish & Tarpon Trust); Aaron Shultz, Eric Schneider, Nick Balfour, and Malcolm Goodman (Cape Eleuthera Institute); Dr. Steve Cooke (Carleton University); Drs. Jeffrey Stein and Cory Suski (University of Illinois).