Tidal effects on habitat selection and aggregation by juvenile pollock Pollachius virens in the rocky intertidal zone

Abstract

Fucoid macroalgae in the rocky intertidal zone are a potentially important foraging and refuging habitat for juvenile fishes. A dominant feature of this habitat is that its availability changes with the tides. Vegetated habitat availability changes in many other systems as well, yet little is known about the effects of these changes on animal distributions. We addressed this problem by studying young-of-the-year pollock Pollachius virens using visual transect surveys in the rocky intertidal zone. We examined tidal effects on pollock distribution, their depth and habitat preferences and the relationship between habitat use and patterns of aggregation. Nearly all the pollock population in our study area moved into the intertidal zone and alternated between aggregation in the open and dispersal in the algae. On rising tides, pollock moved from the subtidal zone to the open intertidal zone in large schools then dispersed among available depths and throughout algal habitats in small schools or as solitary flsh When in algae, pollock preferred the dense algal habitat over the sparse algal habitat. On falling t~d e s , pollock schooled In the open habitat In downshore intertidal and subtidal zones. The main seasonal difference, from early to late summer, was an overall distributional shift towards the downshore open habitat and thv subtidal zone and a preference for greater depths in the intertidal zone. These results support the hypothesis that pollock were using both refuging and schooling antipredator tactics during intertidal zone migrations. We suggest that rocky shores are important nurseries for juvenile pollock.

Movements of Marine Fish and Decapod Crustaceans: Process, Theory and Application

“…In most areas, the overall patterns of distribution are continually changing as individual species move into and out of shallow water at a variety of time scales. For temperate fish, Kuipers (1973), van der Veer and Bergman (1986), Kneib (1987), and Rangeley and Kramer (1995) have recorded higher densities in shallow subtidal waters at low tide than at high tide in both the subtidal and intertidal. This suggests a large influx of fish moving inshore and dispersing over intertidal areas with the flooding tide.…”

Tidal influences on fish distributions on tropical eastern Pacific rocky shores (Colombia)

“…The movement behaviour, however, was related to the diel and tidal cycles in the 3 species, with some of them moving at daylight on the flood tide, while others moved at night on the flood tide. Movements of entire populations from subtidal to intertidal areas, as found by Rangeley & Kramer (1995) in pollock (Pollachius virens, Gadidae) populations, were rare in Utría, although groups of the bumphead damselfish Microspathodon bairdii were found to regularly commute between distinct subtidal and intertidal sites.…”

“…This strategy, classified by Gibson (2003) as intertidal migration, is found in both temperate and tropical intertidal areas (e.g. Kneib 1987, Burrows et al 1994, Rangeley & Kramer 1995, Faria & Almada 2006. However it remains largely unknown how consistent these migrations are at different levels: among species within an assemblage, among individuals within populations and in individuals themselves (Pittman & McAlpine 2003).…”

“…Ansell & Gibson 1990, Burrows et al 1994, rocky shores (Rangeley & Kramer 1995, Faria & Almada 2006, salt marshes (Kneib 1997, Laffaille et al 2000, tropical seagrasses (Robertson 1980, Dorenbosch et al 2004) and mangroves . Apart from intertidal migrations, fishes may use tides to move within and between habitats (Gibson 2003).…”

Explaining Ocean Warming: Causes, scale, effects and consequences

“…In terms of provisioning services, rocky shores are inhabited by a number of edible species that can be exploited as a food or bait resource, for example seaweeds, mussels, winkles, oysters and limpets (Keough et al, 1993;Kyle et al, 1997;Airoldi et al, 2005b;Martins et al, 2010). They can further provide nursery habitat for juvenile commercial fish and shellfish (Rangeley and Kramer, 1995;Silva et al, 2010). Common and abundant macroalgal species may also be harvested for biofuel production (Maceiras et al, 2011) and for biochemical derivatives used for additives to food, cosmetics and pharmaceuticals (Pereira et al, 2013).…”