Publications

Information on fish movement and growth is primarily obtained through the marking and tracking of individuals with external tags, which are usually affixed to anesthetized individuals at the surface. However, the quantity and quality of data obtained by this method is often limited by small sample sizes owing to the time associated with the tagging process, high rates of tagging-related mortality, and displacement of tagged individuals from the initial capture location. To address these issues, we describe a technique for applying external streamer and dart tags in situ, which uses SCUBA divers to capture and tag individual fish on the sea floor without the use of anesthetic. We demonstrate this method for Indo-Pacific lionfish (Pterois volitans/P. miles), species which are particularly vulnerable to barotrauma when transported to and handled at the surface. To test our method, we tagged 161 individuals inhabiting 26 coral reef locations in the Bahamas over a period of 3 years. Our method resulted in no instances of barotrauma, reduced handling and recovery time, and minimal post-tagging release displacement compared with conventional ex situ tag application. Opportunistic resighting and recapture of tagged individuals reveals that lionfish exhibit highly variable site fidelity, movement patterns, and growth rates on invaded coral reef habitats. In total, 24% of lionfish were resighted between 29 and 188 days after tagging. Of these, 90% were located at the site of capture, while the remaining individuals were resighted between 200 m and 1.1 km from initial site of capture over 29 days later. In situ growth rates ranged between 0.1 and 0.6 mm/day. While individuals tagged with streamer tags posted slower growth rates with increasing size, as expected, there was no relationship between growth rate and fish size for individuals marked with dart tags, potentially because of large effects of tag presence on the activities of small bodied lionfish (i.e., <150 mm), where the tag was up to 7.6% of the lionfish's mass. Our study offers a novel in situ tagging technique that can be used to provide critical information on fish site fidelity, movement patterns, and growth in cases where ex situ tagging is not feasible.

This study, co-authored by scientists from REEF's Grouper Moon Project, evaluated genetic connectedness between Nassau Grouper populations throughout the Caribbean. The authors obtained genetic tissue samples from 620 Nassau Grouper from 19 sites across 9 countries, including the Cayman Islands. They found evidence for strong genetic differentiation among Nassau Grouper subpopulations throughout the Caribbean. These results suggest that, despite a lack of physical barriers, Nassau grouper form multiple distinct subpopulations in the Caribbean Sea. Oceanography (regional currents, eddies) likely plays an important role in retaining larvae close to spawning sites at both local and regional spatial scales. These findings highlight the importance of conservation initiatives such at REEF's Grouper Moon program in the Cayman Islands.

The authors describe the behavioral interactions of piscivorous mid-water and demersal fishes at subtropical live-bottom reefs off the coast of Georgia and off the west coast of Florida in the northeast Gulf of Mexico. The observations are used to construct a topological behavior web of the interactions of mid-water and demersal piscivores, their prey, and those associated species that modify predator-prey interactions. Results show that inter-specific behavioral interactions are common attributes of piscivores in these reef fish communities. The authors propose a framework for assessing the demographic consequences of such interactions. Data for this study were collected using a modified Roving Diver Technique, the method employed by REEF surveyors. One of the co-authors, Dave Grenda, is a member of REEF's Advanced Assessment Team.