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Scientists estimate how many fish are caught from Hawai‘i’s reefs

© Frazer McGilvray

Editor’s note: Eva Schemmel is the science adviser for Conservation International Hawaiʻi and an expert on coral reef fisheries.

In Hawaiʻi, fishing isn’t just central to the economy — it’s a vital part of rich cultural traditions across the islands.

But to ensure there are enough fish for tomorrow, islanders need data today, such as how many fish are there — and how many people are out on the water catching them.

That’s critical information a new paper seeks to answer, with a specific focus on the popular fishing grounds of Hawaii’s nearshore reefs. Compared with the data on commercial catch from the open ocean, scientists’ knowledge of fish populations in the coral reefs along the islands’ shores is woefully lacking.

I sat down with the paper’s lead author, Kaylyn McCoy, marine ecosystems research coordinator at the U.S. National Oceanic and Atmospheric Association (NOAA), to discuss how this new information will help the experts managing Hawaiʻi’s reef fish.

Eva Schemmel (ES): In Hawaiʻi, our reef fisheries feed us. Why don’t we know what’s going on in them?

Kaylyn McCoy (KM): In Hawaiʻi, there is no fisher registry, license or permit for these fisheries — and therefore no one knows who is out there fishing. Managers and scientists have a hard time quantifying catch from these fisheries because they include many different fish species, multiple gear types are used and they are spread over large areas and can take place during different times of day and night.

Because of this, there is a lack of good data, especially at the individual island scale. There’s also a gap in available data for fish that thrive in the coral reefs closer to shore. Understanding the status of the nearshore fisheries of each island is critical to understanding patterns, use and sustainability — all things we need to consider when managing our fisheries.

So we set out to discover how many fish are being caught from the reefs near the shores of Hawaiʻi. We know that fishing is integral to the way of life in Hawaiʻi — people fish to make a living, to feed their families, to share time and meals with others or to spend time on the ocean. In order to manage our resources so that we can continue fishing, we need some information about how much fishing is happening now, such as how many people are fishing, and how often do they go? How many fish do they catch on each trip, and how does that add up? We also wanted to know how that compared from island to island.

ES: So how did you get the catch numbers for each island?

KM: We put all the existing data that we could find into models to estimate the total annual catch by gear type (e.g., pole and line) at the island level. The data that we used came from both the commercial and the non-commercial fishing sectors, including subsistence and cultural fishing.

Nearshore fisheries make up less than 2 percent of the reported commercial fishing here in Hawaiʻi, so we really needed to look at the non-commercial sector to better understand the whole story. We looked at the data from multiple sources to compile and estimate how many people were fishing at each island, how many trips they were taking each year and how many fish they were catching on each trip.

ES: What did you find?

KM: The amount of non-commercial fish caught near the shores of Hawaiʻi is massive. Non-commercial fisheries produce more than five times the catch from commercial fisheries — and they make up about 84 percent of the total nearshore catch. Over the span of one year, non-commercial catch is about 900,000 kilograms (about 2 million pounds) compared with commercial nearshore catch, which is under 200,000 kilograms (about 500,000 pounds).

The fact that these numbers are so large adds value to the non-commercial and subsistence fisheries — and shows the importance of people catching fish for cultural, subsistence and recreational reasons (rather than commercial). This data on nearshore fisheries will hopefully help do two things: to give fishers a voice in the local management of these areas; and to make the case for increased funding to develop sustainability initiatives for nearshore fisheries, which will ensure healthy, abundant fish populations for the future.

ES: Now that you’ve got the data, how can it be used?

KM: The experts managing Hawaiʻi’s fisheries, including the nearshore reef fisheries, can use this information on the activities of individual islands to inform their policies. This will make management more effective (there is no one-size-fits-all for all of Hawaiʻi’s islands), therefore enabling nearshore fishing in Hawaiʻi to continue into the future.

Essentially, we gained invaluable information about how often communities go out to fish and the gear they use at each island. For instance, on Oʻahu, the most populated island, only a small number of households engage in fishing, while on Molokaʻi, almost a quarter of all households participate in fishing.

However, if we look at this information in terms of number of trips per year, because the population is much higher on Oahu, there are 15 times the number of trips on Oʻahu compared to Molokaʻi. This means the most fish are coming from Oʻahu, bringing in five times the nearshore reef fish catch of Molokaʻi. This information is important for managers to understand where fishing intensity is most likely impacting the nearshore environment, so they can come up with solutions.

Countries with prominent fishing communities around the world are all deciding the best way to manage their fisheries so that fish populations remain strong, support cultural practices, and people remain fed. The more information we have, the more we can tailor our policies — and the more successful our outcomes will be.

Eva Schemmel is a science adviser for Conservation International Hawaiʻi. Kaylyn McCoy is a marine ecosystems research coordinator at the U.S. National Oceanic and Atmospheric Association (NOAA).

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