Record Details
Food habits and species composition of neritic reef fishes off Depoe Bay, Oregon
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Food habits and species composition of neritic reef fishes off Depoe Bay, Oregon |
| Names |
Steiner, Richard George
(creator) Horton, Howard F. (advisor) |
| Date Issued | 1978-06-12 (iso8601) |
| Note | Graduation date: 1979 |
| Abstract | The distribution and trophic ecology of neritic reef fishes was studied to provide biological information useful in conserving these stocks. Houk and line fishing was conducted from July 1976 to July 1977 on neritic reefs within 5 km of the Oregon coast adjacent to Depoe Bay. Sampling was designed to determine the seasonal and depth variations in species composition of nearshore reef-fish communities, and to determine the trophic relationships within these species. The species composition of fish communities on reefs shoreward of the 20 m depth contour was markedly different from that on deeper (20-50 m) reefs. While fish communities on shallow reefs were dominated by black rockfish (Sebastes melanops), those on deeper reefs were dominated collectively by lingcod (Ophiodon elongatus), yelloweye rockfish (Sebastes ruberrirnus), and black rockfish. The mean lengths of the two most abundant species, black rockfish and lingcod, were decidedly longer on the deep reefs than on the shallow reefs. Several neritic reef fish species were seldom found shoreward of the 20-30 m depth interval, suggesting that this zone constitutes a functional boundary to the distribution of these species. The catch per unit of effort for black rockfish was significantly (p = .01) greater on shallow reefs (10-20 m) during summer and winter than it was during spring and fall. The species composition of catches in all reef areas changed seasonally due mainly to a significant (p = . 10) increase in lingcod abundance in reef areas during their winter spawning period. Analysis of stomach contents of the five principal species using Bray-Curtis dissimilarity indices revealed that these nearshore reef fish communities are relatively uncoupled trophic systems. This suggests that the principal species do not exclude one another from reef areas through competition for food, and thus, for purposes of conservation, can probably be considered separately. Because of the continuing increase in sport and commercial fishing effort on neritic reef fishes, it is increasingly possible that these stocks could be overexploited. Restriction of the lingcod fishery during their winter spawning period and a maximum size limit for lingcod are possible strategies to help insure adequate recruitment of these species. However, before such restrictions are considered, the role of offshore stocks of lingcod with regard to spawning and recruitment needs to be better understood. |
| Genre | Thesis/Dissertation |
| Topic | Fishes -- Oregon -- Depoe Bay |
| Identifier | http://hdl.handle.net/1957/42850 |
