Waves, Beaches and Critical Fish Spawning Habitats: Potential Impacts of Marine Energy Development

Seasonal spawning aggregations occur in the life history of many species of wide-ranging marine fish, in locations that may not be frequented at any other time. Some species make spawning migrations into habitats that are inhospitable for adult survival but beneficial to incubating embryos and hatchlings. Beach spawning fish species are found world wide, and most of these species do not use any other marine habitat for spawning. Beach spawning fishes may mass for several days near shore, timing their spawning to high tides so that oviposition can take place on substrates in the intertidal zone at the water’s edge. Embryos in these locations are regularly or constantly emerged into air by low tides. This benefits the developing young by increasing access to oxygen and providing higher temperatures than surrounding aquatic environments. The waves themselves act as cues for both spawning and hatching processes in these species. Modifications to the wave environment and changes in the spawning habitat may have unpredictable effects on these species during critical phases of the life cycle. These species are important links in food webs of marine mammals, seabirds, and teleost and elasmobranch fishes, and their spawning aggregations attract large predators. Collision, entanglement, entrapment, lights, and disorientation are potential impacts off shore. On shore, changes to waves may impact wave energy, wave angle, and surf zone width, altering cues and spawning habitat for beach spawning fishes. Some potential concerns for ecological risk assessment and monitoring will be addressed with examples from several species of beach spawning fishes on the coasts of North America.