{"id":18839,"date":"2023-12-20T10:46:09","date_gmt":"2023-12-20T15:46:09","guid":{"rendered":"https:\/\/ncseagrant.ncsu.edu\/coastwatch\/?page_id=18839"},"modified":"2024-08-28T14:56:12","modified_gmt":"2024-08-28T18:56:12","slug":"hook-line-science-winter-2024","status":"publish","type":"post","link":"https:\/\/ncseagrant.ncsu.edu\/coastwatch\/hook-line-science-winter-2024\/","title":{"rendered":"Hook, Line & Science: Are Fish Noisier Today Than They Used to Be?"},"content":{"rendered":"\n\n\n\n\n
Ever caught a croaker and heard that weird purring sound? Croaker, along with many other fish such as drum, toadfish and grouper, make noise by way of oscillating their swim bladder.<\/p>\n\n\n\n
Researchers wanted to find a way to capture the \u201csoundscape\u201d of fish in the marine environment without being limited to a fixed location. Ambient sounds and communication within and across species are important to fish and invertebrate survival. Monitoring a waterway\u2019s soundscape can be a useful, harmless, and inexpensive way to complement traditional survey methods in order to understand the presence and activities of a species.<\/p>\n\n\n\n
Until recently, the only method of capturing and recording fish sounds has been to use passive recording devices, like hydrophones and dataloggers, fixed to a specific location. While these instruments are easy to place and remove for study, the chance that they will capture an extended recording of moving fish is relatively small.<\/p>\n\n\n\n
Scientists at East Carolina University deployed a wave glider within Onslow Bay on the North Carolina coast. This ocean-going platform was equipped with sensors to track environmental conditions, monitor and record sound, and identify tagged fish. A system of wings or fins below the platform converts wave energy into forward propulsion, and solar panels power the sensors.<\/p>\n\n\n\n
The team mapped the variation in sounds and species in recordings, and then, to see if the sounds had changed, compared the sounds they recorded to those recorded by the U.S. Navy in the same region over 70 years ago.<\/p>\n\n\n\n
The team first noticed that there were more fish sounds at night than during the day. The collective sounds they identified included weakfish \u201cpurrs,\u201d unidentified drum or croaker \u201cgrunts,\u201d and occasional cusk-eel \u201cchatters.\u201d They also could identify individual fish calls, as well as picking up reef sounds that they were unable to identify.<\/p>\n\n\n\n
Here’s a sample of what they heard:<\/p>\n\n\n\n