Sculpins Reproduction and early life history of the Sculpin Have you ever personally thought that fish were an interesting subject? Most people don’t. The majority of individuals consider fish ordinary, routine and insignificant. However with a closer look, you may discover that fish can be extraordinary and extremely significant in more ways than one. With proper education and better understanding, people will not only realize the importance of the fish, but also the relevance of issues such as the spawning, life history and life span of fish such as Jordania zonope (sculpins). Prior to the spawning season (December-January), the males move into the spawning zone in fresh water or brackish water and are later joined by the females (Krejsa 1967; McAllister and Lindsey 1960), [On-line]. Krejsa (1967) has reported that spawning migration is limited to the coastal population and does not occur in the inland population.
Judging from the location of sculpin larvae taken in this study, both migratory and nonmigratory populations exist. Spawning takes place February through June (Krejsa 1967), [On-line]; mainly in March and April (Moyle 1976), [On-line]; February through May (Millikan 1968), [On-line]; January through September; January through May in Central Valley floor waters; and May through September in the foothill creeks. The average temperature for spawning is 8-13 C (Krejsa 1967). The saltinity is 12 ppt (Millikan 1968); freshwater to intertidal (Moyle 1976); freshwater to oligohaline. Some substrates are large cobbles or flat rocks (Krejsa 1967); under surface of rocks, in beer cans, rusting automobile bodies (Millikan1968), [On-line]; trash (Moyle 1976), [On-line]; under-surfaces or crevices of rocky bottoms and banks, jetties; concrete blocks and other artificial substrates.
For both fresh and salt water sculpins mating activity occurs mostly at night or during darkened conditions. Freshwater male sculpins cleans and prepares a nest cavity for the female to lay her eggs; when the female lays her eggs she deposits them in clusters on the underside of the nest that the male has prepared for her. The saltwater female sculpin chases a male until she traps him in a crevice. She keeps him there until she lays her eggs. A mature male then fertilizes the eggs.
A mature scalyhead sculpin has a well-developed, penis-like appendage that it uses to fertilize the female internally. Sculpin eggs are often brightly colored-green, blue, yellow, orange, pink, red – perhaps to warn off predators. This is a form of protective coloration among many species, which use bright colors to warn predators of danger. The number of eggs that are found in the ovary are 336-5,652 and 700-4,000 per cluster (Krejsa 1967); 584-10,980 eggs in ovary (Bond 1963), [On-line]; 280-7,410 eggs in ovary (Patten 1971), [On-line]; 1,094-5,656 (Millikan 1968), [On-line]. Several females may lay their eggs in one males nest. The female may also lay eggs in more that one males nest.
After the eggs are laid the male goes into the nest and fertilizes the eggs immediately . The male fish guards the nest three to four weeks or until the fry leave. He aerates the eggs by fanning them with his large pectoral fins until hatching occurs (Krejsa 1967), [On-line]. The reason the male fans the eggs is to keeps the eggs clean from bacteria and to keep oxygen flowing to eggs. The male also removes debris and dead eggs with his mouth from his nest.
The father is so attentive, he may net even feed until the eggs hatch. Eggs adhere strongly to one another, but less to other substrates. Incubation is relatively long: 15-16 days at 12 C (Krejsa 1967), 19-20 days at 10-12 C (Mason and Machidori 1976), [On-line] and 14-15 days at nine to 13 C under laboratory conditions. Millikan (1968) noted that hatching rate of prickly sculpin eggs is higher at a salinity of 12 ppt than in fresh water. A Newly fertilized egg is one point four millimeters in diameter.
When the egg is in the stage of morula, it is one point four millimeters in diameter. The egg is one point five millimeters in diameter when it is at the early stage of being an embryo. During the late stages of being an embryo the egg is one point five millimeters in diameter. Most of the sculpins eggs are shaped spherically. The yolk is orange (Krejsa 1967), [On-line]; creamy yellow-white (Millikan 1968), [On-line]; yellowish, partially clear and partially granular. One large oil globule (between zero point two and zero point three millimeters in diameter), with many small oil globules congregating in yolk sac. The chorion is transparent, thick and hard. The Perivitelline space is between zero point one and zero point two millimeters in width.
The eggs are very adhesiveto one another but less so to substrate. The buoyancy of the egg is demersal. Although newly hatched larvae are pelagic and are able to swim immediately (Krejsa 1967; Millikan 1968), [On-line]. The newly hatched prolarva may remain in the nest for a few hours until its body straightens out and it becomes free-swimming. Prickly sculpin for example do not have air bladders; they are usually bottom-dwellers. The very young like to swim just below the surface film so they can float along with the currents. In lakes, newly hatched sculpins swim up to the surface.
It has been suggested that larval sculpin may use surface tension to maintain their position (Mason and Machidori 1976),[On-line]. Larvae remain planktonic and near the water surface for a period of 30-35 days (Krejsa 1967; Mason and Machidori 1976), [On-line]. According to Hershey (1985) “They are especially abundant at the surface during the darkest hours, moving into deeper water during the day. This allows them to feed off tiny plankton, which are most abundant near the surface” (p. 483).
When the Larvae are newly hatched they are between four and seven millimeters in length. The yolk sac is large and spherical in the thoracic region. The oil globules are usually single and are located in the anterior yolk sac, with many small oil globules. At birth the gut is short and coiled in one loop in prolarvae but becomes twisted between one and two times in the prostarvae stage. Their teeth are sharp and pointed at birth.
Size at completion of yolk-sac stage is between five point two and six millimeters. Preanal myomeres 8-12. Post anal myomeres are 22-26, the total myomeres are 32-37. The last fins to complete development are the pelvic fins. The pigmentation of the larvae is large stellate melanophores at base of pectoral fins and mid-ventral and dorsal surface of gut (near anus); a series of melanophores along postanal region. The distribution of the fish are Pelagic (Millikan 1968), [On-line]; planktonic or near the surface of a water column in the shallow end of the shore line and the deep open water of freshwater and oligohaline regions (Phinney, 1972, p.
107). The prickly sculpin for example, range from Seward, Alaska, southward along the Pacific Coast and into adjacent inland waters to the Ventura River in southern California (Barraclough, 1972, p.1922), the prickly sculpin have also been found to be very common in the Sacramento and San Joaquin rivers and estuary. Their present range may be much wider than their historical range, because the planktonic larvae can be distributed via the California Aqueduct, Friant-Kern Canal, and other man-made water transport systems to various portions of southern California. Evidence of the transportation of planktonic larvae is the population of prickly sculpin established in O’Neill Forebay. Sculpin larvae were among the most abundant fishes collected in plankton tows in Suisun Bay and the Delta from March through May. Juveniles become demersal at approximately 15 mm TL (Broadway and Moyle 1978), [On-line] and are common in shallow water with various bottom substrates and shelters.
They may remain in upper estuary waters until early summer of the following year, subsequent. Freshwater and salt water Sculpins are among the most abundant fishes in Alaska. On average the fresh water and salt water Sculpin matures between the ages of two and four years. The fresh water sculpin live in streams and lakes and feed …