Analyses/Maps

Fish

Lingcod HSI map: Potential Distribution

About these maps:
These maps display HSI model results for subadult (left) and adult (right) lingcod during June-November. The maps exhibit the potential distribution of the species based on affinities to bathymetry and substrate (see graphics below maps). Predicted HSI values range in scale from 10 (highest) to 0 (unsuitable) and were grouped into five classes: highest suitability (10-8), moderate (7-5), low (4-2), lowest (1), and unsuitable (0). SI values for bathymetry and substrate type are shown in the graphics below the mapped HSI results. Model performance graphics and statistical details are displayed in the map insets.

Data Sources:
Bathymetry SI: Alverson, 1960; Alverson et al., 1964; Miller and Geibel, 1973; Allen and Smith, 1988; Cass et al., 1990; Wolotira et al., 1993; Wilkins et al., 1998; Lauth, 2001; and Love et al., 2002.
Substrate SI: Quast, 1968a; Quast, 1968b; Miller and Geibel, 1973; Girogi and Congleton, 1984; Richards and Cass, 1985; Shaw and Hassler, 1989; Stein et al., 1990; Hixon et al., 1991; Eldridge, 1994; PFMC, 1999; and CDFG, 2002.
Validation: Wilson-Vandenberg et al., 1996; Wilkins et al., 1998; and Turk et al., 2001.
Life stage information: PFMC, 1999.

Methods:
Bathymetry SI values for adult lingcod were developed using the literature review method, whereas subadult SI values were assigned based on the regression fitting technique using NMFS trawl data. For more detailed descriptions of these techniques, see the discussion of Habitat Suitability Modeling, Section 2.1.2, p. 34.

Results and Discussion:
Adult female lingcod were reported to be considerably larger than males, 760 mm and 500 mm total length, respectively (PFMC, 1999). Minimum size for subadults captured in trawls was 120 mm total length. Subadults were predicted to prefer shallower depths (50-130 m) than adults (50-300 m). Depths > 500 m were considered unsuitable for adults, whereas depths > 350 were unsuitable for subadults. Both adults and subadults prefer hard, rocky substrates; however, preference was moderate for soft substrates. Mapped results for both life stages demonstrate limited areas of highly suitable habitat (rocky areas) and larger areas of moderate suitability throughout the study area. Overall, less than 1% of the available habitat within the study area was predicted highly suitable for adults and subadults. Similarly, areas of high suitability within each sanctuary boundary were restricted to hard substrates and accounted for 1-5% of the total habitat. Conversely, more total area (~20%) was predicted moderately suitable and covered most of the area (< 60%) within Cordell and Gulf of the Farallones sanctuaries. Moderately suitable habitats were also greater in area within Monterey Bay sanctuary, comprising 22% (subadults) - 28% (adults) of the total area.

Model performance was conducted with data from NMFS trawls and CDFG recreational data. Mean abundance from both datasets exhibited a positive relationship with predicted HSI values; however, they were not as strong as other models. Although the results were statistically significant, the data available for SI development were sparse. More data are required to improve SI values and to provide a more robust dataset to test model performance.