Effects of salinity and temperature during incubation on hatching and development of lingcod Ophiodon elongatus Girard, embryos

The interactive effects of salinity and temperature on development and hatching success of lingcod, Ophiodon elongatus Girard, were studied by incubating eggs at four temperatures (6, 9, 12 and 15°C) and five salinities (15, 20, 25, 30 and 35 g L^?1). Hatch did not occur in any of the 15°C treatments. Degree days (°C days) to first hatch was not influenced by temperature or salinity, however, calendar days to first hatch differed significantly for temperature (P<0.0001, 61±1, 44±1 and 35±1 days for 6, 9 and 12°C respectively). Degree days to 50% (427.1±4.2) hatch was not significantly influenced by temperature but was by salinity (P=0.0324). Viable hatch (live with no deformities, 74.1±4.0%) was greatest at 9°C and 25 g L^?1 but not significantly different in the range of 20–30 g L^?1. Larval length (9.4±0.13 mm) was greatest at 9°C and 20–30 g L^?1. Temperature and salinity significantly influenced all categories of deformities with treatments at the upper (12°C and 35 g L^?1) and lower limits (6°C and 15 g L^?1) producing the greatest deformities. The optimal temperature and salinity for incubating Puget Sound lingcod eggs was found to be 9°C and 20–30 g L^?1.     

The effect of light intensity on development and hatching success of lingcod, Ophiodon elongatus (Girard), eggs

The influence of incubation light intensity on development and hatching success of the lingcod (Ophiodon elongatus Girard) was studied by determining time to hatch, per cent hatch (total and viable) and per cent of deformities for embryos incubated at three different light intensities: ～0, 1, and 563 lux. Photoperiod for the last two treatments was 16 h dark: 8 h light. Chemical parameters throughout incubation remained within acceptable ranges. Hatching in all treatments began 43 days post fertilization (353 °C days) and was complete on day 46 (377 °C days), with peak hatch for all treatments on day 44 (361 °C days). Per cent viable hatch for eggs incubated in the 1 lux treatment (88.6 ± 2.1%; mean ± SEM) was significantly greater than eggs incubated in the ～0 lux (59.6 ± 11.3%) and 563 lux (61.4 ± 9.2%) treatments. A significantly greater per cent of deformed embryos with curled bodies occurred at 563 lux (9.5 ± 2.6%) compared with the 1‐lux treatment (2.5 ± 0.6%). No significant differences for the other categories of deformities (ball, short, distended gut) were detected among treatments. Total deformities (all categories combined) for ～0 lux (16.0 ± 4.2%) and 563 lux (17.2 ± 3.3%) were significantly greater than total deformities for 1 lux (5.0 ± 1.4%).     

Occurrence of an exceptional catch of pelagic juvenile lingcod (Ophiodon elongatus) off Point Reyes, California

An exceptionally large catch of pelagic juvenile lingcod (Ophiodon elongatus) was made just offshore of Point Reyes, California in 1990. Results of 678 midwater trawls from annual surveys from 1983 to 1990 show that pelagic juvenile lingcod have a strong nearshore distribution and were most abundant in the Gulf of the Farallones, with a mean abundance of 5.0 per trawl. Otoliths from fish taken in the large catch were used to estimate parameters of a log-transformed Gompertz growth model, which was then used to calculate hatch dates. Hatching peaked around 24 March and ranged from 10 March to 19 April, implying a January-February spawning season for lingcod off central California. The large catch was associated with an anticyc-lonic eddy which would lead to water being trapped near the coast; convergence of fish associated with the eddy may have been due to either physical or biological effects.