Trends in body size across an environmental gradient: A differential response in scavenging and non-scavenging demersal deep-sea fish

Collins, Martin A.; Bailey, David M.; Ruxton, Graeme D.; Priede, Imants George

doi:10.1098/rspb.2005.3189

Cited by 103 publications

(99 citation statements)

References 39 publications

(61 reference statements)

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“…Also, similar declines (table 1) are seen in fishes with widely different lifestyles (e.g. scavenging and non-scavenging fishes; Collins et al 2005), making it seem less likely that a change in prey species composition could cause such a widespread effect. It is also unlikely that changing carrion availability has had a significant long-term effect.…”

Section: Discussionmentioning

confidence: 71%

Long-term changes in deep-water fish populations in the northeast Atlantic: a deeper reaching effect of fisheries?

et al. 2009

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A severe scarcity of life history and population data for deep-water fishes is a major impediment to successful fisheries management. Long-term data for non-target species and those living deeper than the fishing grounds are particularly rare. We analysed a unique dataset of scientific trawls made from 1977 to 1989 and from 1997 to 2002, at depths from 800 to 4800 m. Over this time, overall fish abundance fell significantly at all depths from 800 to 2500 m, considerably deeper than the maximum depth of commercial fishing (approx. 1600 m). Changes in abundance were significantly larger in species whose ranges fell at least partly within fished depths and did not appear to be consistent with any natural factors such as changes in fluxes from the surface or the abundance of potential prey. If the observed decreases in abundance are due to fishing, then its effects now extend into the lower bathyal zone, resulting in declines in areas that have been previously thought to be unaffected. A possible mechanism is impacts on the shallow parts of the ranges of fish species, resulting in declines in abundance in the lower parts of their ranges. This unexpected phenomenon has important consequences for fisheries and marine reserve management, as this would indicate that the impacts of fisheries can be transmitted into deep offshore areas that are neither routinely monitored nor considered as part of the managed fishery areas.

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Section: Discussionmentioning

confidence: 71%

Long-term changes in deep-water fish populations in the northeast Atlantic: a deeper reaching effect of fisheries?

et al. 2009

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“…A study of trends in bony fish size between 500 and 5000 m depth in the northeast Atlantic shows that scavenging species are bigger at greater depths whereas there is no significant size trend in non-scavengers. Metabolic modelling of foraging strategies shows a clear advantage of increased size of scavengers in the oligotrophic environment of the abyss (Collins et al 2005). It is evident from figure 4 that Chondrichthyes are predominantly bigger fish than Actinopterygii.…”

Section: (A) Volume Of Ocean Occupied By Chondrichthyesmentioning

confidence: 97%

The absence of sharks from abyssal regions of the world's oceans

et al. 2006

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The oceanic abyss (depths greater than 3000 m), one of the largest environments on the planet, is characterized by absence of solar light, high pressures and remoteness from surface food supply necessitating special molecular, physiological, behavioural and ecological adaptations of organisms that live there. Sampling by trawl, baited hooks and cameras we show that the Chondrichthyes (sharks, rays and chimaeras) are absent from, or very rare in this region. Analysis of a global data set shows a trend of rapid disappearance of chondrichthyan species with depth when compared with bony fishes. Sharks, apparently well adapted to life at high pressures are conspicuous on slopes down to 2000 m including scavenging at food falls such as dead whales. We propose that they are excluded from the abyss by high-energy demand, including an oil-rich liver for buoyancy, which cannot be sustained in extreme oligotrophic conditions. Sharks are apparently confined to ca 30% of the total ocean and distribution of many species is fragmented around sea mounts, ocean ridges and ocean margins. All populations are therefore within reach of human fisheries, and there is no hidden reserve of chondrichthyan biomass or biodiversity in the deep sea. Sharks may be more vulnerable to over-exploitation than previously thought.

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“…Rodríguez and Lewis, 1997). Second, there is evidence that fish size decreases with increases in depth (Rex et al, 2006;Thiel, 1975), although these trends may differ among different functional groups (Collins et al, 2005).…”

Section: Acuity Light Level and Turbiditymentioning

confidence: 99%

Visual acuity in ray-finned fishes correlates with eye size and habitat

Caves

Sutton

Johnsen

2017

Journal of Experimental Biology

106

137

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Visual acuity (the ability to resolve spatial detail) is highly variable across fishes. However, little is known about the evolutionary pressures underlying this variation. We reviewed published literature to create an acuity database for 159 species of ray-finned fishes (Actinopterygii). Within a subset of those species for which we had phylogenetic information and anatomically measured acuity data (n=81), we examined relationships between acuity and both morphological (eye size and body size) and ecological (light level, water turbidity, habitat spatial complexity and diet) variables. Acuity was significantly correlated with eye size (P<0.001); a weaker correlation with body size occurred via a correlation between eye and body size (P<0.001). Acuity decreased as light level decreased and turbidity increased; however, these decreases resulted from fishes in dark or murky environments having smaller eyes and bodies than those in bright or clear environments. We also found significantly lower acuity in horizon-dominated habitats than in featureless or complex habitats. Higher acuity in featureless habitats is likely due to species having absolutely larger eyes and bodies in that environment, though eye size relative to body size is not significantly different from that in complex environments. Controlling for relative eye size, we found that species in complex environments have even higher acuity than predicted. We found no relationship between visual acuity and diet. Our results show that eye size is a primary factor underlying variation in fish acuity. We additionally show that habitat type is an important ecological factor that correlates with acuity in certain species.

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Trends in body size across an environmental gradient: A differential response in scavenging and non-scavenging demersal deep-sea fish

Cited by 103 publications

References 39 publications

Long-term changes in deep-water fish populations in the northeast Atlantic: a deeper reaching effect of fisheries?

Long-term changes in deep-water fish populations in the northeast Atlantic: a deeper reaching effect of fisheries?

The absence of sharks from abyssal regions of the world's oceans

Visual acuity in ray-finned fishes correlates with eye size and habitat

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