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Geology topics

Ryan M. Tharp

Publications and source records attributed to Ryan M. Tharp.

2 recordsLinked to original sources

Home ranges of economically important reef fishes at North Carolina artificial reefs

Home range is a vital component to understanding animal ecology and can vary with factors like species, body size, and habitat. Artificial reefs are increasingly used to supplement or enhance habitat for reef fish. Quantifying reef fish home range sizes and the factors affecting home ranges is thus critical to understanding the efficacy of artificial reefs to sustain communities that reflect those on natural reefs. We estimated home ranges of reef fishes at artificial reefs in the southeast United States, evaluated what factors affected those home ranges, and compared them to home ranges of similarly sized fish on natural reefs. From June–October 2021 and 2022, we deployed acoustic tags on five fishery targeted reef species, black sea bass ( Centropristis striata ), gag ( Mycteroperca microlepis ), greater amberjack ( Seriola dumerili ), almaco jack ( S. rivoliana ), and red snapper ( Lutjanus campechanus ), on four artificial reefs near Cape Lookout, North Carolina. Tagged fish were tracked using a fine-scale positioning system for ~ 120 days. Home ranges varied by species and fish size (i.e., total length). Black sea bass had the smallest home ranges (mean = 6266 m 2 ), gag and red snapper had moderate home ranges (38,265 m 2 and 53,553 m 2 , respectively), and almaco jack and greater amberjack had the largest (152,146 m 2 , and 414,107 m 2 , respectively). Black sea bass, gag, and red snapper displayed increased home range size with total length while greater amberjack and almaco jack home ranges remained relatively constant across lengths. Greater amberjack home ranges were further influenced by artificial reef complex area with an increase in reef area leading to a larger home range. Our data from artificial reefs showed considerable overlap in the relationship between home range and body size when compared to similarly sized predatory reef fish on natural reefs. This information will be vital in improving ecological understanding of how artificial reefs can influence area use of reef-associated species to help inform future artificial reef deployments. Moreover, these results provide an important comparison between artificial reefs and natural reefs as habitats for reef-associated species, a topic that will become increasingly important as the quantity of artificial structures in our oceans increases. deployments. Moreover, these results provide an important comparison between artificial reefs and natural reefs as habitats for reef-associated species, a topic that will become increasingly important as the quantity of artificial structures in our oceans increases.

North Carolina

Artificial structure selection by economically important reef fishes at North Carolina artificial reefs

Artificial reefs can play an important role in marine fisheries management by supplementing or enhancing natural habitats. Despite their increased use in recent years, the choice of structures used at artificial reefs remains largely haphazard due to the lack of information on reef structure performance. Few studies have examined the use of different artificial reef structures by individual fish. From 2021-2022, we acoustically tagged 72 black sea bass ( Centropristis striata ), 34 gag ( Mycteroperca mircrolepis ), 27 greater amberjack ( Seriola dumerili ), nine almaco jack ( S. rivoliana ), and eight red snapper ( Lutjanus campechanus ) on four artificial reef complexes near Cape Lookout, North Carolina, U.S. Available artificial reef structures consisted of materials of various sizes and heights made of concrete and metal. We tracked tagged fish using a fine-scale positioning system for ~100 days. Black sea bass exhibited high site fidelity to the artificial structure where we caught them, rarely moving away from that structure. The limited movement resulted in low transition probabilities; we conclude that black sea bass do not select for particular artificial structures. Gag and red snapper moved greater distances away from artificial structures and routinely moved between them. Greater amberjack and almaco jack moved the most within the complexes displaying circling behavior around individual structures and were the only species that regularly moved off the artificial reef complexes. Greater amberjack movements away from artificial sites were most commonly directed to surrounding shipwrecks. Whereas gag, red snapper, almaco jack, and greater amberjack used all available structures, they consistently selected for high relief structures, such as vessels, more than other structures. These results will be useful to managers charged with decisions on what types of structures to place at artificial reef complexes to supplement or enhance habitat for economically important fishes.

North Carolina