September 22, 2021 — Rockfish have an affinity for structure, whether it is created by rocks, corals, or sponges. But do deep-sea coral and sponge ecosystems offer benefits beyond structure? Are fish in these habitats more productive?
A new NOAA Fisheries study is the first to look at the relationship between fish condition and reproductive success in a variety of habitats, focusing on deep-sea coral and sponge ecosystems. As part of the study, scientists are developing methods to accurately assess rockfish condition by measuring fat content. For rockfish in Alaska, fat means healthy.
The study looked at the most commercially important rockfish in the Gulf of Alaska and Aleutian Islands: northern rockfish and Pacific ocean perch. Samples are being collected during 2021–2022 Alaska Fisheries Science Center bottom trawl surveys.
The research addresses a priority of the North Pacific Fishery Management Council: understanding the importance of deep-sea coral and sponge ecosystems to commercially valuable fish.
“Developing a feasible method to accurately measure fish condition across Alaska waters during annual surveys will provide a wealth of data to help us understand how habitat influences fish productivity. That knowledge will also help us track how climate change is affecting the ecosystem,” said study leader Christina Conrath, NOAA Fisheries biologist at the Alaska Fisheries Science Center.
The new project is part of NOAA’s Alaska Deep-Sea Coral and Sponge Initiative, which is supported by the Deep Sea Coral Research and Technology Program. The initiative was established to provide the scientific data needed to inform management and protection of deep-sea coral and sponge ecosystems in Alaska. Discoveries made previously and under this initiative have greatly advanced our knowledge of corals and sponges and their role in Alaska marine ecosystems.
Rockfish in Alaska waters are frequently found in coral and sponge habitat. Previous Alaska Fisheries Science Center research found that rockfish densities were highest in structurally complex habitat. But that research showed no evidence that structure created by corals and sponges was more important than that formed by rocks.
“We know that rockfish get value from structure. But we don’t really have evidence yet that coral and sponge habitat offers benefits beyond structure,” Conrath said. “We’re exploring that.”