Behavioral Response of Crayfish to a Fish Predator

Abstract

In laboratory aquaria, smallmouth bass (Micropterus dolomieui) influenced activity, substrate selection, behavior, and food consumption of crayfish (Orconectes propinquus) of different sizes and sexes. In the presence of a predator, crayfish selected substrates affording most protection, significantly modified the frequency of various behavior patterns, and reduced their overall activity. Active behavior patterns such as walking—climbing and feeding were suppressed while defensive patterns, such as burrowing and chelae display increased. Grazing by crayfish on their detrital food supply was also suppressed by bass. Degree of response of crayfish appeared correlated with liability to predation, i.e., small, vulnerable crayfish were most affected, whereas large, less vulnerable crayfish were least affected. Because crayfish ♂ ♂ have larger chelae than ♀ ♀, they apparently were better able to defend themselves against predators; consequently, less vulnerable ♂ ♂ did not modify their behavior as dramatically as ♀ ♀. In field collections crayfish exposed on the substrate were larger than those buried; fewer ♀ ♀ than ♂ ♂ were exposed. Thus, field observations correlated well with laboratory findings, suggesting that predators affect distribution and behavior of crayfish in natural communities. By affecting several trophic levels within aquatic systems, influence of predators goes beyond simple interactions of predator and prey.

Why do juvenile fish utilise mangrove habitats?

“…These results differ to those for several other species in which the introduction of shelter had little or no effect on spatial distribution in the absence of predators (Werner et al, 1983a;Utne et al, 1993). However, there are many examples showing that in the presence of predators, aquatic fauna shift to areas offering improved shelter from predation (Stein, 1977;Stein and Magnuson, 1976;Sih, 1982;Vuorinen et al, 1983;Power et al, 1985;Utne et al, 1993). Thus, in terms of the hypothesis of predation risk, decreased risk of predation appears to be an important factor underpinning the preferred use of mangrove habitats by juvenile fish.…”

“…Unlike small fish, larger animals did not flee to shelter in the presence of predators. Small and large sunfish and several other species (Stein and Magnuson, 1976;Sih, 1982;Werner et al, 1983a) show a similar behaviour, and in general, there is a paucity of large piscivorous predators in shallow water habitats (Blaber, 1980;Ansell and Gibson, 1990). With growth, increased size affords either a refuge in size or greater mobility and ease of escape from predators, which allows successful migration towards the deep-water habitat of adult populations via more open estuarine habitats.…”

Habitat Preference of Different Size Classes of Austropotamobius Pallipes in an Irish River

“…Adults will prefer deeper waters to escape terrestrial predators, such as otters and minks, which represent a greater danger to a large crayfish. Adult crayfish can avoid predation by fish, even when exposed (STEIN and MAGNUSON, 1976;STEIN, 1977;DORN and MITTELBACH, 1999). This could possibly explain why adults were not found in the vegetation and leaf litter (which were generally shallow) at Carragh bridge, although depth throughout the river at this site varies little.…”

Habitat Suitability Index Relationships for the Northern Clearwater Crayfish,Orconectes Propinquus (Decapoda: Cambaridae)

“…This suggests that increasing amounts of coarse substrates correlates with increases in O. propinquus CPUE and may be differentially important for various life stages. Crayfish substrate preference is typically associated with the most overall cover and protection from predators [24,45]. Larger crayfish prefer larger substrate sizes since the larger substrates will provide more overall interstitial spaces.…”