Numerous studies in the Northeast U.S. have shown that adult marine fish distributions are changing, but few studies have looked at the early life stages of those adult fish to see what is happening to them over time.
(From Science Daily) — A new study by NOAA Fisheries researchers has some answers, finding that distributions of young stages and the timing of the life cycle of many fish species are also changing.
Most marine fish have complex life histories with distinct stages — much like frogs. Marine fish spawn small planktonic eggs, approximately 1/20 of an inch in diameter, that move at the whim of ocean currents. These eggs hatch into larvae that have non-functional guts, un-pigmented eyes, and often don’t yet have a mouth. Over a period of weeks to months, while drifting in the ocean, larvae develop and grow until they reach a point where they transition into juveniles recognizable as a fish. This complex life history is similar to that of frogs, which grow from eggs to tadpoles to adult frogs.
The distribution of larvae in the sea is determined by where adult fish reproduce and by currents that move these small early life stages around the ocean. In a study published September 23 in the journal PLOS ONE, researchers from NOAA’s Northeast Fisheries Science Center (NEFSC) used long-term survey data to compare the distributions of larvae between two decades, from 1977-1987 and from 1999-2008. They also used long-term survey data to compare distributions of adult fish over the same time period.
Read the full article here: http://www.sciencedaily.com/releases/2015/10/151001125828.htm