The feeding habits of slope dwelling macrourid fishes in the eastern North Pacific

The relatively unobtrusive deep-sea camera system Eye-in-the-Sea (EITS) was deployed in Monterey Bay Canyon, California, USA, to assess the relative photosensitivity of 2 deepsea fishes, Coryphaenoides acrolepis and Anoplopoma fimbria. Previous studies addressing the in situ response of deep-sea fishes to red and white light were done in the presence of ROV-induced stimuli. Here, we report on the behavioral response of C. acrolepis and A. fimbria in a vehicle-free environment when subjected to white (full visible spectrum), red (685 nm), and far-red (695 nm) illumination in situ. Under far-red light conditions, A. fimbria spent significantly more time in the fieldof-view and demonstrated an increase in entrances/exits when compared to the situation under red-light and white-light conditions. No significant difference in the average time C. acrolepis spent in the field-of-view was found between any of the test wavelengths; however, the entrances-to-exits ratio for C. acrolepis decreased during white-light conditions. While A. fimbria often displayed a flight response at the onset of white and sometimes red (685 nm) illumination, C. acrolepis did not demonstrate a similar behavioral response when exposed to light within its range of visual sensitivity. A. fimbria undergo a dramatic ontogenic shift in depth, inhabiting well-lit, near-shore waters as juveniles and moving into deeper waters as adults. It is thought that C. acrolepis spend part of their early life history in the light-limited mesopelagic, below the permanent thermocline, and move into deeper waters as they mature. Based on the results of the present study, we hypothesize that systematic differences in the phototactic responses of deep-sea fishes are a function of life history as well as spectral sensitivity. KEY WORDS: Deep sea · Red light · Fish behaviorResale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESS

Section: Discussionmentioning

confidence: 99%

Behavioral responses of two deep-sea fish species to red, far-red, and white light

Raymond¹,

Widder²

2007

“…Predator diets are becoming increasingly recognized as a valuable means to gain information on cephalopod distribution and abundance within oceanic ecosystems (Drazen et al 2001, Cherel et al 2004, Clarke 2006, Staudinger et al 2013. Predators serve as 'biological samplers,' and cephalo pod beaks obtained from stomach contents have also been used to better understand the dynamics of oceanic food webs, especially in the Southern Ocean (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…The giant grenadier diet (by mass) is represented by Gonatidae, Octopoteuthis spp., fish remains, and a small contribution by the vampire squid (Drazen et al 2001). Octopoteuthis deletron and V. infernalis were also abundant among the prey remains of SBMNH 8991 and were also present in the stranded whale from Monterey that preyed on the giant grenadier (Adams et al 2015).…”

Section: Fish Contribution To Dietmentioning

confidence: 98%

Diet of Cuvier’s beaked whales Ziphius cavirostris from the North Pacific and a comparison with their diet world-wide

West¹,

Walker²,

Baird³

et al. 2017

Cuvier's beaked whales Ziphius cavirostris are distributed world-wide and are recognized as vulnerable to anthropogenic noise. They are the most common cetacean to strand in temporal and spatial proximity to navy sonars. Cuvier's beaked whales are known for their extreme diving capabilities, but diet information, fundamental to understanding foraging at depth, is limited from most regions. We report on 11 441 prey items from stomach contents of 16 stranded or bycaught specimens collected between 1976 and 2016 across the North Pacific. Overall diet was composed of cephalopods, fish, and crustaceans, but was dominated by cephalopods. Thirty-seven cephalopod species representing 16 families contributed 98

“…Amphipods may be responsible for much of the consumption of some food falls, and fall prey to macrourids, liparids, zoarcids, or other predators. Typically, only large macrourids are photographed at bait (King et al 2006), and only large specimens have carrion in their stomachs (Drazen et al 2001), suggesting that small individuals are unable to compete for resources at food falls or actively avoid them due to predation risk. Ontogenetic increases in the size of the olfactory lobe of Coryphaenoides armatus indicate a shift from visual to olfactory cues (Wagner 2003), which may also influence the reduced response of small macrourids to odor plumes.…”

Section: Response Of Scavengers To the Macrourid Odor Plumementioning

confidence: 99%

Response of deep-sea scavengers to ocean acidification and the odor from a dead grenadier

Barry¹,

Drazen²

2007

Experiments to assess the impact of ocean acidification on abyssal animals were performed off Central California. The survival of caged megafauna (Benthoctopus sp., Pachycara bulbiceps, Coryphaenoides armatus) exposed to CO 2 -rich and normal (control) seawater varied among species. Benthoctopus sp. and P. bulbiceps survived control conditions and month-long episodic exposure to acidic, CO 2 -rich waters (pH reductions of ~0.1 U). All C. armatus in both treatments died, potentially due to cage-related stress, predation, and exposure to acidic waters. High survival by P. bulbiceps and Benthoctopus under month-long exposure to CO 2 -rich waters indicates a physiological capacity to cope, at least temporarily, with stresses that will accompany expected future changes in ocean chemistry. The abundance of free-ranging scavengers was not correlated with variation in pH levels near fish cages. Incidental observations of abyssal scavengers collected using time-lapse cameras during these experiments were used secondarily to evaluate the hypothesis that macrourid fishes avoid the odor of dead conspecifics. Caged macrourids in view of time-lapse cameras died within 2 to 3 d, eliciting a strong response from the regional scavenger assemblage which aggregated near the cage. The pattern of scavenger visits suggests avoidance among taxa and a succession of scavengers. Macrourids, a dominant abyssal scavenger, either did not respond to the death of their congener or possibly avoided the area. Lack of a response by macrourids may be due to (1) avoidance of sites of dead or dying congeners, (2) high sensitivity to ocean acidification, (3) low nutritional value or weaker odor plumes from carcasses of abyssal versus shallow-water taxa, or (4) rapid departure from sites where a carcass is inaccessible. Camera systems were not deployed in view of carcasses at control sites (away from CO 2 pools) during each experiment, and we therefore cannot exclude the possibility that the pattern of scavenger visits was influenced by elevated carbon dioxide levels.KEY WORDS: Food fall · Behavior · Macrouridae · Coryphaenoides armatus · Zoarcidae · Pachycara bulbiceps · Octopodidae · Benthoctopus sp. Resale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESS