Manooch and fisheries agent Jim 

 Bahen agree spawning plays a ma- 

 jor role in North Carolina's sea- 

 sonal fish migrations. 



"Herring, striped bass and 

 sturgeon migrations are stricdy 

 based on spawning/ 7 Manooch 

 says. Other species like spot, 

 whiting and croaker make their 

 moves to spawn ; too ; Bahen adds. 



Most fish spawn over a large 

 geographical area and over a long 

 period of time ; so it ; s hard to pin- 

 point details on each species. But 

 fisheries experts realize healthy 

 spawning grounds such as North 

 Carolina's estuaries and natural 

 and artificial reefs are vital. 



"If we lose those/ 7 Bahen says ; 

 "we ; U see a decline in the species. 77 



Food may be another reason fish 

 migrate. When larger species detect 

 that their food sources of smaller 

 fish are moving on ; they follow 

 them. 



But North Carolina has plenty 

 of food fish year-round ; Bahen 

 argues. "Something triggers that 

 inner clock and says you better 

 start moving south. 77 



It ; s water temperature, say most 

 fishermen. 



Fish are cold-blooded ; explains 

 Sea Grant agent Bob Hines. When 

 the water gets too hot or too cool 7 

 they move to an area where it ; s 

 more preferable ; he says. 



"The water temperature is the 

 key/ 7 Manooch says. "There are 

 preferred water temperatures for all 

 species. They stay in the water 

 temperature they want/ 7 



King mackerel 7 for example 7 like 

 65- to 70-degree water. Bluefish 

 like the thermometer to read 68 

 degrees. 



Most fish such as tuna ; billfish 

 and blues have about a 7-degree 

 range of water temperatures they 

 favor ; Manooch says. 



Other theories suggest imprint- 

 ing or certain scents lead fish 

 home. Stars may play a part for 

 some other fish. And one West 

 Coast researcher is testing the cor- 

 relation between magnetism and 

 migration with fish that have bits 

 of magnetite in their snouts. 



Environmental changes and re- 

 production are the two primary 

 motives for migration, says Bori 

 OUa ; a fish behavior scientist at 

 the Cooperative Institute for 

 Marine Resource Studies in New- 

 port, Oregon. 



If conditions for fish or any 

 other animals are constant and 

 food is plentiful, they don't need 

 to move, Olla says. But if a fish 

 could not survive in one place 

 because of temperatures or a 

 change in its food source, it is 

 selectively advantageous for the 



fish and its species as a whole to 

 migrate. 



Bluefish 7 for example, migrate 

 south in the fall to escape low 

 water temperatures and scarce food 

 sources. They travel where they 

 can "get more energy from the en- 

 vironment/ 7 Olla says. This leads 

 to higher productivity and larger 

 populations. 



His research in Sandy Hook, 

 N.J. ; and in Oregon points to 

 temperature and light as the forces 

 that trigger migration. 



"We 7 re pretty sure light— day 

 length— becomes a signal to the 

 animal/ 7 Olla says. 



Since the 1920s, researchers have 

 known that the time animals are 

 exposed to light invokes hormonal 

 changes. Somehow that link be- 

 tween light and hormones triggers 

 migrations. 



The right combination of light 

 and temperature spurs the fish to 

 move. 



While scientists search for 

 answers, angler Harvey Elam 

 waits in the surf off Bald Head 

 Island for a run of red drum. 



