Influence of environmental variables on the distribution of Squatina guggenheim (Chondrichthyes, Squatinidae) in the Argentine–Uruguayan Common Fishing Zone

Vögler, Rodolfo; Milessi, Andrés C.; Quiñones, Renato A.

doi:10.1016/j.fishres.2007.11.028

Cited by 37 publications

(40 citation statements)

References 29 publications

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“…Vooren and Da Silva () revealed that juvenile Squatina guggenheim of both sexes occurred close to shore, while adult sharks were distributed offshore up to 100 m depth. Vögler et al () also found that the different habitat preferences of S. guggenheim are linked to an increase in body size. For other sharks (e.g.…”

Section: Discussionmentioning

confidence: 93%

Population structure, distribution and habitat use of the Critically Endangered Angelshark, Squatina squatina, in the Canary Islands

Meyers

Tuya

Barker

et al. 2017

Aquatic Conservation

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Angel sharks are among the most threatened fish worldwide, facing regional and global extinction. In Europe, populations of the three Critically Endangered angel sharks (Squatina aculeata, Squatina oculata and Squatina squatina) have been severely depleted. Taking advantage of the last global ‘hotspot’ of the angelshark, Squatina squatina, this study gathered data through a citizen science programme to describe the occurrence of this shark in the coastal waters of the Canary Islands. Specifically, this study described (1) the population structure, and (2) habitat use of this species, which was used in a Species Distribution Model to (3) examine realized and potential distribution patterns, and to (4) determine the relative importance of environmental predictors on the occurrence of S. squatina. Over the 12 months sampling period (April 2014 – March 2015), 678 sightings were reported. Individuals ranged from 20 to 200 cm (total length). Larger sightings of both females and neonates occurred mostly in April to July, i.e. during the pupping season. Males were significantly more frequent in November to January, i.e. during the mating season. Angelsharks were encountered at depths from <1 m to a maximum of 45 m. Small‐sized individuals (i.e. neonates) exclusively occurred in shallow water (0–25 m). Most sharks occurred on sandy bottoms adjacent to reefs. Even though sightings were recorded at all seven islands in the archipelago, there were fewer encounters in the western than the eastern islands. The Species Distribution Model indicated that the probability of occurrence mainly correlated with sea surface temperature, chlorophyll, salinity and depth. Areas with the greatest habitat suitability were in shallow water. The angelshark displayed spatial (vertical and horizontal) and temporal segregation by size and sex. This information is vital to inform conservation of this Critically Endangered shark in its last stronghold.

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Section: Discussionmentioning

confidence: 93%

Population structure, distribution and habitat use of the Critically Endangered Angelshark, Squatina squatina, in the Canary Islands

Meyers

Tuya

Barker

et al. 2017

Aquatic Conservation

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“…Water temperature is believed to be one of the most important environmental variables determining the distribution of sharks in coastal environments [21], [22], [23], [24], with water temperatures in False Bay playing an important role in determining seasonal fish assemblages and abundance in the bay’s surf-zones [25]. Water temperatures in False Bay vary seasonally from a mean winter temperature of 13.2°C to a mean summer temperature of 21.5°C [25].…”

Section: Discussionmentioning

confidence: 99%

The Influence of Environmental Variables on the Presence of White Sharks, Carcharodon carcharias at Two Popular Cape Town Bathing Beaches: A Generalized Additive Mixed Model

Weltz

Kock²,

Winker³

et al. 2013

PLoS ONE

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Shark attacks on humans are high profile events which can significantly influence policies related to the coastal zone. A shark warning system in South Africa, Shark Spotters, recorded 378 white shark (Carcharodon carcharias) sightings at two popular beaches, Fish Hoek and Muizenberg, during 3690 six-hour long spotting shifts, during the months September to May 2006 to 2011. The probabilities of shark sightings were related to environmental variables using Binomial Generalized Additive Mixed Models (GAMMs). Sea surface temperature was significant, with the probability of shark sightings increasing rapidly as SST exceeded 14°C and approached a maximum at 18°C, whereafter it remains high. An 8 times (Muizenberg) and 5 times (Fish Hoek) greater likelihood of sighting a shark was predicted at 18°C than at 14°C. Lunar phase was also significant with a prediction of 1.5 times (Muizenberg) and 4 times (Fish Hoek) greater likelihood of a shark sighting at new moon than at full moon. At Fish Hoek, the probability of sighting a shark was 1.6 times higher during the afternoon shift compared to the morning shift, but no diel effect was found at Muizenberg. A significant increase in the number of shark sightings was identified over the last three years, highlighting the need for ongoing research into shark attack mitigation. These patterns will be incorporated into shark awareness and bather safety campaigns in Cape Town.

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“…The potential importance of physical and biotic factors in habitat selection by sharks has been reviewed by Simpfendorfer & Heupel (2004) and has been addressed by approximately 75% (n = 79) of the studies included in our review (Table S1 in the supplement). Influences such as tide, water temperature, salinity, dissolved oxygen, substratum type and depth affect the distribution of coastal elasmobranchs, with greater responses for some species and size classes (Economakis & Lobel 1998, Ackerman et al 2000, Hopkins & Cech 2003, Simpfendorfer et al 2005, DeAngelis et al 2008, Vogler et al 2008, Campos et al 2009, Heithaus et al 2009b, Ubeda et al 2009). To date, depth and temperature have been measured with shark movement for many species, followed by tide, current, benthos type, salinity, prey and dissolved oxygen associations (Table 2).…”

Section: Habitat Specificitymentioning

confidence: 99%

Complexities of coastal shark movements and their implications for management

Speed

Field²,

Meekan

et al. 2010

Mar. Ecol. Prog. Ser.

275

239

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Global declines of shark populations are of concern because of their largely assumed role as moderators of ecosystem function. Without long-term data on movement patterns for many species, it is impossible to infer relative extinction risk, which varies as a function of range, dispersal and habitat specificity and use. The past 50 yr of research on coastal sharks has revealed common movement patterns among species. In the horizontal plane, measured home range size generally increases with body size. We demonstrate meta-analytically the effects of increasing body size and monitoring time on home range size. Changes in the extent of horizontal movement might arise from ontogeny, predator avoidance or environmental tolerances. In the vertical plane, movement patterns include oscillatory vertical displacement, surface swimming, diel vertical migration and swimming at depth. These vertical movements are often attributed to foraging or navigation, but have been quantified less than horizontal patterns. Habitat specificity is often correlated with environmental conditions such as depth, salinity, substratum, and in some cases, prey availability. Site fidelity is common in species that use nursery areas. However, fidelity to mating, pupping, feeding and natal sites has only been observed in a few species. To date, few studies have examined habitat partitioning, although some general patterns have emerged: habitats appear to be subdivided by benthos type, prey availability and depth. The conservation of coastal sharks can be facilitated in some cases by the use of marine protected areas, especially for coastal resident species using specific nursery, reproduction or feeding areas. Partial protected-area closures might be effective during aggregation or migration periods to protect older size classes, but these must be applied with other management strategies such as reduced fishing and size or bag limits to protect individuals throughout different life history phases. More long-term research on habitat use, migration patterns and habitat partitioning is essential for developing successful management initiatives for coastal shark populations.

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Influence of environmental variables on the distribution of Squatina guggenheim (Chondrichthyes, Squatinidae) in the Argentine–Uruguayan Common Fishing Zone

Cited by 37 publications

References 29 publications

Population structure, distribution and habitat use of the Critically Endangered Angelshark, Squatina squatina, in the Canary Islands

Population structure, distribution and habitat use of the Critically Endangered Angelshark, Squatina squatina, in the Canary Islands

The Influence of Environmental Variables on the Presence of White Sharks, Carcharodon carcharias at Two Popular Cape Town Bathing Beaches: A Generalized Additive Mixed Model

Complexities of coastal shark movements and their implications for management

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