The predatory role of lingcod (Ophiodon elongatus) in the San Juan Archipelago, Washington. Anne H. Beaudreau

ISBN: 9781109314533

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NOOKstudy eTextbook

193 pages


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The predatory role of lingcod (Ophiodon elongatus) in the San Juan Archipelago, Washington.  by  Anne H. Beaudreau

The predatory role of lingcod (Ophiodon elongatus) in the San Juan Archipelago, Washington. by Anne H. Beaudreau
| NOOKstudy eTextbook | PDF, EPUB, FB2, DjVu, audiobook, mp3, RTF | 193 pages | ISBN: 9781109314533 | 10.29 Mb

Lingcod (Ophiodon elongatus) play a key role as high trophic level consumers in rocky reef food webs along the west coast of North America. In Washington inshore waters, lingcod are among a suite of recreationally harvested rocky reef fishes thatMoreLingcod (Ophiodon elongatus) play a key role as high trophic level consumers in rocky reef food webs along the west coast of North America.

In Washington inshore waters, lingcod are among a suite of recreationally harvested rocky reef fishes that have declined in abundance over recent decades. This dissertation addresses critical gaps in knowledge of lingcod feeding ecology and behavior to gain insight into the role of lingcod predation in structuring prey populations and the ecological consequences of fishing for demersal food webs of the San Juan Archipelago, Washington. Chapters One and Two quantified patterns of lingcod predation on rockfishes (Sebastes spp.). Rockfishes were a common component of adult lingcod diets, making up 11.0% of the total diet by mass.

Although lingcod are capable of ingesting large rockfish, diet data suggested that they may more commonly consume small-bodied rockfish species, including Puget Sound rockfish ( Sebastes emphaeus), and juvenile stages of larger rockfishes (e.g., copper rockfish, S. caurinus). Consumption models were developed to determine population-level consumption of rockfishes by lingcod in marine reserves (areas closed to fishing) and non-reserves in the San Juan Channel. Based on these models, rockfish consumption by lingcod was estimated to be 5--10 times greater in marine reserves than in non-reserves.

In Chapter Three, acoustic methods were used to quantify lingcod movement patterns and describe the distribution of pelagic fishes to make inferences about the temporal and spatial conditions in which lingcod feeding on pelagic prey occurs. Lingcod maintained small summer ranges (21,272 +/-13,630 m2) almost exclusively within rocky reef habitat. Depths occupied by lingcod typically ranged from 0 to 50 m and coincided with depth distributions of pelagic fishes- however, diel patterns in lingcod activity varied inversely with biomass of pelagic fishes on the rocky reef.

Chapter Four evaluated the degree to which movement of adult lingcod connects marine reserve and non-reserve populations. Individual lingcod exhibited strong site fidelity and limited movement over scales of days to months. Demographic differences between neighboring rocky reefs suggest relatively long-term persistence in local lingcod population structure, possibly due to low rates of mixing.



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