Analyses/Maps

Fish

Canary rockfish HSI map: Potential Distribution

About these maps:
These maps display HSI model results for subadult (left) and adult (right) canary rockfish 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 et al., 1964; Miller and Hardwick, 1973; Gunderson and Sample, 1980; Tagart and Kimura, 1982; Dark et al., 1983; Eschmeyer et al., 1983; Allen and Smith, 1988; Weinberg, 1994; Wilkins et al., 1998; Yoklavich et al., 2000; Lauth, 2001; and Love et al., 2002.
Benthic substrate SI: Boehlert, 1980; Boehlert and Kappenman, 1980; Rosenthal, 1982; Stein et al., 1990; PFMC, 1999; CDFG, 2002; and Love et al., 2002.
Validation: Wilson-Vandenberg et al., 1996; Wilkins et al., 1998; and Turk et al., 2001.
Life stage information: Love et al., 2002.

Methods:
Bathymetry SI values for adult canary rockfish were developed using the literature review method, while 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 canary rockfish were determined by length-at-maturity information (Love et al., 2002) where females > 440 mm and males > 400 mm total length. Subadults ranged in size from the adult minimum sizes to 110 mm total length. Adult depth suitability was highest from 50-249 m with moderate suitability extending out to depths of 299 m. Depth suitability for subadults (based on NMFS trawl data) was highest from 50-89 m and probably extends to nearshore waters (Love et al., 2002), however, since trawl data were absent in waters < 50 m this could not be modeled. Unsuitable depths were considerably shallower for subadults (> 170 m) than adults (> 850 m). Literature sources revealed a shift in substrate affinity at maturation from soft sediments to hard substrate. This shift in habitat affinity yields significant differences in the HSI model results. Less than one percent of the available habitat within the study area was predicted highly suitable for adults, whereas almost 10% was highly suitable for subadults. This trend was also consistent within all sanctuaries where predicted highly suitable habitat for adults comprised 1.8 % of available habitat and 23% for subadults. Approximately half of the total area of Gulf of the Farallones sanctuary was predicted to be highly suitable for subadults, whereas these areas were smaller in percent coverage in Cordell Bank (27%) and Monterey (16%) sanctuaries. Highly suitable habitats for subadults were located within a broad area on the continental shelf throughout the study area and moderate suitability extended to the shelf edge. All highly suitable habitats for adults were contained within one of the three sanctuary boundaries.

Model performance was assessed with June-November CDFG recreational catch data. Both adult and subadult models exhibited strong positive correlations with CDFG data. Additional life history information is recommended to further refine depth and substrate SI’s and additional catch data will help assess model performance.