Papers by Gregor Cailliet
Canadian Journal of Fisheries and Aquatic Sciences, 2005
The alternating translucent and opaque banding pattern in canary rockfish (Sebastes pinniger) oto... more The alternating translucent and opaque banding pattern in canary rockfish (Sebastes pinniger) otoliths, aged using a break-and-burn methodology, are annual markings. To validate age assignment, we compared measured radiocarbon levels in canary rockfish ...
Long-term trends in the elasmobranch assemblage of Elkhorn Slough,
Monterey Bay, California, were... more Long-term trends in the elasmobranch assemblage of Elkhorn Slough,
Monterey Bay, California, were analyzed by documenting species composition and catch per unit effort (CPUE) from 55 sport
fishing derbies that occurred during May, June, and July, from 1951 until 1995. The most abundant species (bat ray, Myliobatis
californica; shovelnose guitarfish, Rhinobatos productus; and leopard shark, Triakis semifasciata) were also analyzed for size-weight relationships, trends in size class distribution, stage of maturity, and sex
ratios. Changes in species composition over the course of the derbies included the near complete disappearance of shovelnose guitarfish
by the 1970’s and a slight increase in the abundance of minor species (mainly smoothhounds, Mustelus spp., and thornback,
Platyrhinoidis triseriata) starting in the mid 1960’s. The relative abundance of bat rays in the catch steadily increased over the years while the relative abundance of leopard sharks declined during the last
two decades. However the average number of bat rays and leopard sharks caught per derby declined during the last two decades.
Fishing effort appeared to increase over the course of the derbies. There were no dramatic shifts in the size class distribution data for bat rays, leopard sharks, or shovelnose guitarfish. The catch of bat rays
and leopard sharks was consistently dominated by immature individuals, while the catch of shovelnose guitarfish was heavily
dominated by adults. There was evidence of sexual segregation in either immature or mature fish in all the species. Female bat rays and shovelnose guitarfish were larger than their male counterparts and outnumbered males nearly 2:1. Female and male leopard sharks were more nearly equal in size and sex ratio. Changes in species composition
are likely due to fishing pressure, shifts in the prevailing oceanographic conditions, and habitat alteration in Elkhorn Slough. The sex ratios, stage of maturity, and size class distributions provide further evidence for the theory that Elkhorn Slough functions as a nursery habitat for bat rays and leopard sharks.
Bulletin of Marine Science Miami, 2007
We provide a detailed description of growth zone counts at two locations in the skeletal structur... more We provide a detailed description of growth zone counts at two locations in the skeletal structure of four bamboo coral colonies (Family Isididae, sub-family Keratoisidinae, genera Lepidisis spp. and Keratoisis sp. from New Zealand). Zone counts were made microscopically on skeletal cross-sections of calcareous internodes producing counts of up to 90 for Lepidisis spp. and 160 for Keratoisis sp. Scanning Electron Microscope (SEM) images taken of cross-sections at the junction of the calcareous internode and gorgonin node revealed clear zone resolution and produced counts that were substantially higher (a maximum 490 zones). Lead-210 dating was applied to the skeletal structure of one specimen of Lepidisis sp. to develop an independent estimate of age and growth. Radial micro-sampling of the skeletal carbonate indicated the age of the colony at the largest section (7.4 mm average radius) was 43 yrs old (26-61 yrs 95% CI), with an average radial growth rate of 0.18 mm yr -1 (0.13-0.29 mm yr -1 95% CI). Comparisons between the three age estimates for Lepidisis sp. were made and it was hypothesized that zones observed by light microscope have a bi-annual periodicity and that SEM-observed zones at the nodal juncture may represent an environmental event, such as lunar periodicity.
Estuaries and Coasts, Mar 1, 1996
Food habits of the dominant fishes collected from 1974 to 1980 at eight locations in Elkhorn Slou... more Food habits of the dominant fishes collected from 1974 to 1980 at eight locations in Elkhorn Slough, California, and the adjacent ocean were investigated. Epifaunal crustacea was the major prey group identified from stomach contents of more than 2,000 fishes, followed by epifaunal and infaunal worms, and mollusca. Overall, 18 &h species consumed 263 different prey taxa, ranging from 10 taxa to 125 taxa per fish species and including 99 crustacean, 56 polychaete, and 39 molluscan taxa. Mean prey richness was greatest at stations near the ocean and lowest at inshore stations. Detailed dietary data for all prey taxa were summarized as trophic spectra for each fish species. Trophic spectra represented functional groups of prey and were used for comparisons of dietary similarity. Cluster analyses, based on tropbic spectra, resulted in four feeding guilds of fishes. Of 18 fish species, seven (Amphistidw
Rockfishes (Sebastes spp.) support one of the most economically important fisheries of the Pacifi... more Rockfishes (Sebastes spp.) support one of the most economically important fisheries of the Pacific Northwest and it is essential for sustainable management that age estimation procedures be validated for these species. Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon (¹C) signal in the ocean environment that scientists have identified as a useful tracer and
Great White Sharks, 1996
Page 1. CHAPTER 9 Using Allometry to Predict Body Mass from Linear Measurements of the White Shar... more Page 1. CHAPTER 9 Using Allometry to Predict Body Mass from Linear Measurements of the White Shark HENRY F. MOLLET Monterey Bay Aquarium Monterey, California GREGOR M. CAILLIET Moss Landing Marine Laboratory ...
A multi-disciplinary study to assess the importance of small-scale refugia to species of large ro... more A multi-disciplinary study to assess the importance of small-scale refugia to species of large rockfishes in deep water was undertaken recently in Monterey Bay. Isolated rock habitat at depths suitable for rockfishes in Soquel Canyon (up to 300 m ) was identified using finescale bathymetry and sidescan sonar imaging, verified with visual observations from a manned submersible, mapped and quantified. Species composition, size, and habitat specflcity (type and depth) of fishes associated with these features were estimated using a video camera and parallel laser system along transects made from a submersible. High numbers of large (up to 1 m ) rockj7shes were locally associated with rock ledges, small caves, crevices, and overhangs. Two distinct assemblages of rockfishes were obvious from clustering analysis; small species were associated with mud and cobble substrata of low reliex while larger species were found under ledges or near large structures on vertical walls, ridges and boulder fields. Relative abundance and size of the largest species were higher and larger, respectively, when estimated from submersible surveys than from partyboat catch records from adjacent areas. We suggest that discontinuous rock outcrops of high relief are inaccessible fishing areas and thereby provide natural refuge f o r commercially and recreationally important fishes in Soquel Canyon.
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Papers by Gregor Cailliet
Monterey Bay, California, were analyzed by documenting species composition and catch per unit effort (CPUE) from 55 sport
fishing derbies that occurred during May, June, and July, from 1951 until 1995. The most abundant species (bat ray, Myliobatis
californica; shovelnose guitarfish, Rhinobatos productus; and leopard shark, Triakis semifasciata) were also analyzed for size-weight relationships, trends in size class distribution, stage of maturity, and sex
ratios. Changes in species composition over the course of the derbies included the near complete disappearance of shovelnose guitarfish
by the 1970’s and a slight increase in the abundance of minor species (mainly smoothhounds, Mustelus spp., and thornback,
Platyrhinoidis triseriata) starting in the mid 1960’s. The relative abundance of bat rays in the catch steadily increased over the years while the relative abundance of leopard sharks declined during the last
two decades. However the average number of bat rays and leopard sharks caught per derby declined during the last two decades.
Fishing effort appeared to increase over the course of the derbies. There were no dramatic shifts in the size class distribution data for bat rays, leopard sharks, or shovelnose guitarfish. The catch of bat rays
and leopard sharks was consistently dominated by immature individuals, while the catch of shovelnose guitarfish was heavily
dominated by adults. There was evidence of sexual segregation in either immature or mature fish in all the species. Female bat rays and shovelnose guitarfish were larger than their male counterparts and outnumbered males nearly 2:1. Female and male leopard sharks were more nearly equal in size and sex ratio. Changes in species composition
are likely due to fishing pressure, shifts in the prevailing oceanographic conditions, and habitat alteration in Elkhorn Slough. The sex ratios, stage of maturity, and size class distributions provide further evidence for the theory that Elkhorn Slough functions as a nursery habitat for bat rays and leopard sharks.
Monterey Bay, California, were analyzed by documenting species composition and catch per unit effort (CPUE) from 55 sport
fishing derbies that occurred during May, June, and July, from 1951 until 1995. The most abundant species (bat ray, Myliobatis
californica; shovelnose guitarfish, Rhinobatos productus; and leopard shark, Triakis semifasciata) were also analyzed for size-weight relationships, trends in size class distribution, stage of maturity, and sex
ratios. Changes in species composition over the course of the derbies included the near complete disappearance of shovelnose guitarfish
by the 1970’s and a slight increase in the abundance of minor species (mainly smoothhounds, Mustelus spp., and thornback,
Platyrhinoidis triseriata) starting in the mid 1960’s. The relative abundance of bat rays in the catch steadily increased over the years while the relative abundance of leopard sharks declined during the last
two decades. However the average number of bat rays and leopard sharks caught per derby declined during the last two decades.
Fishing effort appeared to increase over the course of the derbies. There were no dramatic shifts in the size class distribution data for bat rays, leopard sharks, or shovelnose guitarfish. The catch of bat rays
and leopard sharks was consistently dominated by immature individuals, while the catch of shovelnose guitarfish was heavily
dominated by adults. There was evidence of sexual segregation in either immature or mature fish in all the species. Female bat rays and shovelnose guitarfish were larger than their male counterparts and outnumbered males nearly 2:1. Female and male leopard sharks were more nearly equal in size and sex ratio. Changes in species composition
are likely due to fishing pressure, shifts in the prevailing oceanographic conditions, and habitat alteration in Elkhorn Slough. The sex ratios, stage of maturity, and size class distributions provide further evidence for the theory that Elkhorn Slough functions as a nursery habitat for bat rays and leopard sharks.