Varied response of garden eels to potential predators and other large-bodied organisms

Abstract

Garden eels live in burrows from which they protrude their bodies to feed on planktonic organisms, show courtship behavior and reproduce, and in which they seek refuge from predators. Despite universal acceptance that garden eels retract into their burrows for predator avoidance, a surprising lack of published accounts of this behaviour exists. Here, opportunist observations made during shark abundance video surveys, show reactions of garden eels during encounters with potential predators and other large-bodied organisms. Brown garden eels (Heteroconger longissimus) were observed during ten encounters with larger fish, and showed variable responses to five different large-bodied species. Varied responses suggested an ability to discriminate between organisms and react according to relative predation risk and proximity. The largest reactions were in response to encounters with piscivorous teleosts, the most likely predators of garden eels. Multiple encounters with two species of sharks, both improbable predators, resulted in a less pronounced reaction, consistent across encounters but variable with proximity. An encounter with a non-predator teleost resulted in the mildest response, despite very close proximity. These observations suggest that garden eels have the ability to discriminate between large-bodied organisms, and react according to relative predation risk.

Effects of exposure to large sharks on the abundance and behavior of mobile prey fishes along a temperate coastal gradient

“…In recent years, an increasing number of studies have used baited remote underwater video stations (BRUVs) in order to non-invasively sample mobile fish populations, a technique that can detect elusive species which may be missed by underwater visual census [46] and is particularly effective for mobile fishes and for sampling in areas where fish may be scarce [47]. Several studies have used BRUVs to analyze predator-prey dynamics involving sharks [15], and to examine how predation risk influences behavior in mobile fish species [33,48,49]. The majority of BRUV studies have been performed on hard substrata on and around coral and rocky reefs, both due to the expectation for increased biodiversity on videos collected near reefs, as well as the improved visibility resulting from a lack of loose sediments [50]; however, BRUVs have also been utilized to study fish assemblages in unconsolidated, high sediment marine environments like those in the temperate waters of the Northwestern Atlantic [51].…”