Cynoscion othonopterus
| Cynoscion othonopterus | ||||||||||||
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| Cynoscion othonopterus | ||||||||||||
| Jordan & Gilbert , 1882 | ||||||||||||
Cynoscion othonopterus ( English Gulf weakfish ) is a Umberfisch (drumfish). It lives exclusively in the Gulf of California and is listed as threatened on the red list of endangered species .
features
The fish has a silvery-blue-gray color on its back, the scales are covered with small dark spots and the tips of the fins are yellowish in color. Specimens up to 70 cm long and weighing up to 2.4 kg have been caught.
Habitat and behavior
Cynoscion othonopterus lives in the sea as well as in brackish water in subtropical latitudes in water depths from the surface to about 30 m depth. The species lives exclusively in the northern Gulf of California on an estimated distribution area of 20,000 km², with the juveniles growing up in the brackish water of the mouth of the Colorado River . However, as little water from the river reaches the estuary due to increasingly high water consumption, the habitat of the young animals is shrinking noticeably. Cynoscion othonopterus is not dangerous to humans and is popular as a sport and food fish. Due to overfishing and the already small distribution area, the fish is now on the Red List as threatened . Studies from 1998 to 2002 found a decrease in the average height of up to 10 cm, which is considered an indicator of overfishing.
More recent studies from 2014 suggest unusual mating behavior: Researchers found that Cynoscion othonopterus generates an extremely loud courtship noise to attract potential breeding partners in the mating season that takes place every year in April and May. Schools of fish with up to 1.5 million individuals were documented that had gathered over a length of 27 km for mating purposes. The noises could be recorded with underwater microphones and reached a volume of 150 decibels with peaks of up to 177 decibels, the loudest sound made by fish. The underwater noises can generate resonances on the hull of fishing boats and can therefore be clearly heard above water, which enables fishermen to easily track down the schools. The researchers concluded that the volume of the mating calls could even be large enough to cause lasting damage to the hearing of other sea creatures.
literature
- LN Chao (1995): Sciaenidae. Corvinas, barbiches, bombaches, corvinatas, corvinetas, corvinillas, lambes, pescadillas, roncachos, verrugatos. In: Pacifico centro-oriental. Volume 3, pages 1427-1518.
Web links
- Cynoscion othonopterus on Fishbase.org (English)
Individual evidence
- ↑ Fishbase - Cynoscion othonopterus
- ↑ Red List of Threatened Species - Cynoscion othonopterus
- ↑ Brad E. Erisman, Timothy J. Rowell: A sound worth saving: acoustic characteristics of a massive fish spawning aggregation . Ed .: Biology letters. December 20, 2017, doi : 10.1098 / rsbl.2017.0656 .