From counting fish on video to federal management actions
Appropriately assessing and managing marine fish stocks requires several data inputs which include information on age and growth, reproduction, and fishery-dependent data such as commercial and recreational landings and discards. One key data source that is becoming increasingly important is data from fishery-independent surveys, which track trends in key population metrics independent from landings or other information directly tied to the fishery. To meet this need, several fishery-independent surveys have been established to track population trends of managed fishes in the Gulf of Mexico. While some of these efforts include traditional capture methods such as trawling or hooked gear, the high diversity of species typically associated with untrawlable reef habitats has necessitated the use of alternative survey methods, most notably underwater video.
Figure 1
The use of underwater video, especially the use of stereo-baited remote underwater video arrays (Figure 1), is an increasingly common approach used worldwide to identify and count reef-associated fishes. These camera systems can be deployed remotely without impacting the habitats being sampled. These camera systems are also generally less selective than traditional capture gears such as nets or hooked gears, allowing them to observe a wide range of species and sizes. In the Gulf of Mexico, this approach was first implemented in the early 90’s by the NOAA Southeast Fisheries Science Center’s (SEFSC) Pascagoula laboratory in association with the Southeast Area Monitoring and Assessment Program (SEAMAP), and data from this survey have long been integral to federal reef fish assessments. While this survey extends from Texas to the Dry Tortugas, it is primarily restricted to high-relief reef habitats along the shelf break. To address the spatial limitations of this survey, the SEFSC Panama City laboratory initiated another survey in 2006 focusing primarily on shallow reefs in the northeastern Gulf. Subsequently, FWRI’s Fishery-Independent Monitoring program (FIM) established a third complementary survey in 2008 that initially focused on waters off Tampa Bay and Charlotte Harbor, but was expanded throughout the eastern Gulf beginning in 2014 through funding from the National Fish and Wildlife Foundation following the Deepwater Horizon Oil Spill.
Although these three surveys differ in terms of their spatial coverage, each uses identical sampling gear to derive fish counts on a diverse set of habitats throughout the Gulf. Historically, each survey independently provided data for stock assessment through the SouthEast Data, Assessment, and Review (SEDAR; sedarweb.org) process. During this process, all available data are critically evaluated by a panel of experts that determines which data are appropriate to include in the assessment. While fishery-independent data are essential to these stock assessments, the inclusion of information from multiple, duplicative surveys can be problematic if there is disagreement in long-term trends. To compensate for these issues, novel statistical techniques have been developed and implemented by FIM researchers to account for differences in sampled habitats and spatial footprints among the three surveys. By doing so, data from all three surveys can be combined, resulting in a single, comprehensive index of relative abundance and size composition across the full survey domain (see Figure 2). This information is incorporated into the assessment models to determine stock status that is used by the Gulf of Mexico Fishery Management Council to develop management advice.
Figure 2. Trends in scamp (Mycteroperca phenax) observed on the three individual Gulf video surveys, and the combined index of abundance ultimately used in the federal assessment.
To date, data from FWRI FIM video surveys have been combined and integrated into the assessment of several species: Gray Snapper, Vermilion Snapper, Scamp, Gag, Red Grouper, Gray Triggerfish, Hogfish, and Greater Amberjack. In addition to stock assessments, observed trends can also be used to determine the effects of environmental perturbations including red tide, invasive species, and climate change. Through continued collaborative efforts among these three groups, these surveys have recently been integrated under a unified sampling design and program; the Gulf Fisheries-Independent Survey of Habitat of Ecosystem Resources (G-FISHER). This initiative began in 2020 and is supported for the next 5 – 10 years by funding from the NOAA RESTORE Science program.