Habitat ecology
  Little is known of the natural biology of any squid species on the west coast other than their distributions. Species include the commercially harvested Doryteuthis (Loligo) opalescens, the giant squid Moryteuthis robusta, the stubby squid Rossia pacifica and, recently, the Humboldt squid Dosidicus gigas. Giant squids Architeuthis spp. have also been recorded from the North Pacific area through strandings.
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  Squids
  Studies on habitat ecology of octopuses and their relatives are arranged by taxon. Studies on squids are presented here, while those on ENTEROCTOPUS and other species of OCTOPUS can be found in other sections.
 
Research study 1
 

Giant squids Moroteuthis robusta are known from sightings, strandings, and catchings by commercial fishers generally during gill-netting for salmon. There are about 30 records of strandings and catchings for Puget Sound alone since the late 1940s. The number of commercial "catches"suggests that the squids may be tracking salmon returning to coastal regions during the summer and autumn seasons. Anderson 1996 Of Sea & Shore 19: 111.photograph of tentacle of giant squid Moroteuthis robusta showing clawed suckersphotograph of internal organs of giant squid Moroteuthis robusta

 

Claws on the suckers of Moroteuthis robusta have given it the common name "clubhook" squid

Internal anatomy of a male 3.5m M. robusta dissected in an
invertebrate zoology class at the University of British Columbia.
The ctenidia of this specimen are heavily infested with a parasitic
copepod (visible as black dots on the yellowish-coloured ctenidia).

 
Research study 2
 

Architeuthis squids are not common along the west coast, but the smaller Moroteuthis robustus is seen quite often.  In the decades from 1960s to 1980s their novelty prompted researchers to document sightings but, later, it became apparent that commercial fisherfolk were bringing specimens up in trawl nets at regular intervals, and several government fisheries labs had many specimens stored in freezers.  Some reports are given here:

Carmel, California:  the author reports an incident of 3 SCUBA-divers catching a 2.3m specimen of M. robustus during a dive.  No details are given (whether spear-guns, nets, hand-to-hand, or whatever), but one guesses that it would not be a trivial thing to subdue a healthy specimen.  Phillips 1961 Calif Fish Game 47: 416.

Trinidad Head, California:  this reports deals with 3 specimens caught by trawlers in 200-300 fathoms, but the author refers to 6 additional individuals reported from California waters, including the one in the previous report, up to the date of this study. The largest of the 3 individuals measures 3.3m from mantle tip to extended tentacle tip. The author notes that M. robustus is the largest west-coast invertebrate.  Smith 1963 Calif Fish Game 49: 209.

Santa Barbara, California: records of 7 specimens caught by commercial fishing boats between 1967-74 from depths of 200-300m in the Santa Barbar Channel.  Mean length (posterior mantle tip to extended tentacle tip) of the 7 specimens is 2.5m, and female:male ratio is 6:1.  Other statistics on various body-portion lengths and some masses are provided for 6 of the 7 animals.  The author notes the first appearance of Humboldt squids Dosidicus gigas off the coasts of southern California in summer 1974.  Hochberg 1974 The Tabulata 7: 83. 

Victoria, British Columbia: this report is the first documentation of a stranding of giant squids M. robustus on the British Columbia coast, but the author acknowledges several previous records of squids being caught.  Green 1989 Calif Fish Game 75: 242.

 
Research study 3
 

map showing collection sites for squids Doryteuthis opalescens for genetics studyDoes a free-swimming, oceanic species like Doryteuthis opalescens show genetic differentiation throughout its distributional range? The answer to this question is of interest to conservation biologists and fisheries officers whose management policies may be improved by identification of sub-sections of the population.  According to the authors, past attempts to answer this question have mostly employed allozyme electrophoresis, a less robust methodology for detecting genetic polymorphism than the one employed here.  The authors use microsatellite (polymorphic DNA) markers from 6 loci to assay allele frequencies in squids from 11 sites ranging from southern British Columbia to northern Baja California (see map).  Results show genetic homogeneity throughout the species range, indicating high levels of gene flow, and confirming the findings of earlier studies.  Reichow & Smith 2001 Mol Ecol 10: 1101; see also Reichow & Smith 1999 Mar Biotechnol 1: 403.

 
Research study 4
 

photograph of Humboldt squids in situ in Monterey Bay, courtesy Monterey Bay Aquarium Research Institute, CaliforniaSixteen years of near-continuous video records from deep-submersible expeditions (ROV) in the Monterey Submarine Canyon by scientists at the Monterey Bay Aquarium Research Institute provide unique documentation of northward range expansion of Humboldt squids Dosidicus gigas.  The researchers correlate the northward expansion into waters off central California with climate-linked oceanographic changes and reduction in competing top predators, notably, tuna and billfish species.  Both types of fishes are known to feed on juvenile Dosidicus.  Based on their records, the researchers propose that Dosidicus in central California now represent a sustained population, rather than a sequence of multiple invasions.  Of  concern is their major potential impact on a valuable groundfish, Pacific hake, known to be a favoured prey.  Prior to the arrival of Dosidicus, hake populations were steady, but during initial forays of the squids into the area and from their major incursion in 2002, population numbers have declined and have remained low. Zeidberg & Robinson 2007 Proc Nat Acad Sci USA 104 (31): 12948. Photograph courtesy the authors and the Monterey Bay Aquarium Research Institute, California MBARI.

NOTE  the videos, more than 3000 in number, provide depth-coverage exceeding 1000m.  The first appearance of Dosidicus in Monterey Bay was in 1997, coincidental with strong El Niño conditions.  Their next significant and on-going appearance was in 2002, again following an El Niño event

 

Humboldt squids Dosidicus gigas at at 500m depth
in Monterey Bay. The smelt is 15cm in length

 
Research study 5
 

activity pattern for squid Dosidicus gigas over a 3d period in the Gulf of CaliforniaInformation on diving depths of Humboldt squids Dosidicus gigas in the Gulf of California is provided in a joint project by researchers from several U.S. and Mexican research institutions.  The researchers attach satellite-linked dive recorders to 3 individuals and monitor their behaviour for a period of 5-7d.  Results show that the squids spend about 75% of daylight hours and about 50% of nighttime hours at 200-400m depth (see representative graph for part ofa record for one of the squids).  The remaining half of nighttime is spent at shallower depths (<200m).  These nighttime excursions into warmer surface waters (about 21oC, but up to 28oC) are followed by a return to the 200-400m depths where the squids appear to remain quiescent for at least part of the time. The researchers think that this is a time of recovery from metabolic stress incurred in the warm surface waters, but it could also be a time photograph of stranded squid Dosidicus gigas, courtesy Josie Osborne,





for initital digestion of prey eaten at the surface. Note though that the selection of these periods of quiescence by the authors is rather arbitrary. Davis et al. 2007 Mar Ecol Progr Ser 333: 291. Photograph courtesy Josie Osborne, Raincoast Education Society, Tofiino, British Columbia.

NOTE  similar recorders are attached also to 5 sperm whales Physeter macrocephalus in the same region in the hope of matching behavioral patterns of the 2 species.  However, the authors’ interpretation of the results in the context of predator-prey interactions between them are rather speculative and are not included here

Humboldt squid Dosidicus gigas stranded on the beach 1X

 

 
Research study 6
 

map showing distributions of large Pacific squids Dosidicus gigas and Sthenoteuthis oualaniensisAn interesting study by a consortium of west-coast researchers (California, Mexico, and Chile) on the genetic makeup of populations of large squids Dosidicus gigas and Sthenoteuthis oualaniensis in the eastern Pacific reveals distinct genetic breaks at 5-6oN latitude.  Both species, although D. gigas to a lesser extent, are divided into northern and southern hemisphere populations.  The authors discuss possible reasons for the divergence, including oceanographical and ecological.  One possibility relates to an eastward jutting extension of a zone of low oxygen concentration at 300m depth at about 10oN latitude, close to the biogeographic-break zone (see map), thought possibly to provide protection to the squids from cetacean predators while the squids hunt their own prey at depth.  Staaf et al. 2010 Mar Ecol Progr Ser 418: 165.

NOTE  this subtropical species occurs on the west coast of North America only south of Baja California and thus is not really part of the west-coast fauna

NOTE  this is the Eastern Pacific oxygen-minimum zone (see map)

 
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