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Fishery monitoring research compares traditional and high-tech methods

This project, funded by NOAA's Coral Reef Conservation Program through the Caribbean Fishery Management Council, explores three methods of collecting fish survey data during fish spawning aggregations. Which method will be the most effective and efficient? We hope to answer that question.

Red hind grouper swims along seafloor
Red hind swimming along the seafloor. Photo by Pichon Duarte

The Caribbean Fishery Management Council is one of the eight regional fishery management councils for the conservation and orderly utilization of the fishery resources of the USA - specifically this council manages those fisheries of Puerto Rico and USVI. The council is responsible for the creation of fishery management plans for fishery resources (or, FMPs) in the US Caribbean Exclusive Economic Zone (EEZ) off PR and USVI. They fund research that supports our understanding of how fishery resources are being exploited, and explores ways in which we can better sustain these resources. Isla Mar has been conducting research for the CFMC for many years now. Let's talk about our current project --

Hear the Hind, See the Hind: Validation of Acoustic, ROV and Divers’ data collected during spawning season to monitor marine protected areas coupled with oceanographic observations

In this project, our team is working with colleagues to conduct fish surveys using three different methods -- audio stereo remote underwater video (AS-RUV), remotely operated vehicle (ROV) and diver-based surveys. These surveys are conducted during fish spawning aggregations when certain fish can be found in much larger numbers than outside of spawning season.

But what are fish spawning aggregations (FSAs)?

FSAs are temporary gatherings of large numbers of conspecific (= the same species) fish for the purpose of reproduction. They are critical events in the life history of the species, often representing the only opportunities for reproduction and thus comprise the major source of the reproductive output for an entire population.

Why should we care?

Governments, commercial fisheries and small-scale and subsistence fisher should care about their conservation because FSAs support some of the most important and productive commercial, recreational, and subsistence fisheries across the globe, and multi-species FSAs sites often represent the most important regional fishing grounds.

How do we monitor fish communities?

Well, we can use two different approaches, and often using both together is the best bet. These are known as fishery-independent and fishery-dependent monitoring. Let's explore them.

  • Fishery-independent monitoring is a method that evaluates fish communities by assessing fish species abundance and sizes to inform management about population status. FIM does not consider or include catch data from the fishery. This method can be conducted during FSA formation.

  • Fishery-dependent monitoring assesses standing stocks of fish and invertebrate species through analyzing landing data and catch/effort of the industry, for example. This method relies on fishers to report their catch and effort in a standardized way. We do not rely on this method during closed seasons (while FSAs are formed) but it can be used outside of those seasons.

A diver performing a fish survey
Dr. Evan Tuohy conducting a fish survey. Photo by JP Zegarra

What are the high-tech survey methods?

We are also using ROVs and AS-RUVs. A remotely operated vehicle is an unoccupied, highly maneuverable underwater machine that can be used to explore ocean depths while being operated by someone at the water surface. They allow us to explore the ocean without actually being in the ocean.

While using ROVs eliminates the “human presence” in the water, in most cases, ROV operations are simpler and safer to conduct than any type of occupied-submersible or diving operation because operators can stay safe on ship decks. ROVs allow us to investigate areas that are too deep for humans to safely dive themselves, and ROVs can stay underwater much longer than a human diver, expanding the time available for exploration.

The audio stereo remote underwater video (AS-RUV) uses hydrophones (underwater microphones) and stereo video to record both audio and video of the fish populations surrounding the system. Just like an ROV, this system does not require a diver to operate it. The AS-RUV can be left underwater for an extended period of time. This system can observe fish spawning aggregations in its natural setting without potentially influencing this process using bait, such as with a baited remote underwater video (BRUV) camera system.

But can these newer methods really replace the efficiency of a highly trained surveyor that can count and assess fish populations in real-time? We seek to answer this question through this project. Stay tuned to find out more!

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