Distribution of whale shark (Rhincodon typus) off northern Peru based on habitat suitability

Abstract

1. In the south-eastern Pacific Ocean, few studies of whale sharks (Rhincodon typus) exist. In Peru, the northern coast has been identified as the area with the highest presence of whale sharks, yet their ecology in this area is poorly defined.2. This study predicts the spatial distribution of whale sharks off coastal northern Peru (03 00 0 S-04 30 0 S) during La Niña and El Niño seasonal conditions, utilizing maximum entropy modelling. Between 2009 and 2018 (except for 2011), 347 whale sharks were geo-referenced in northern Peru with greatest data recordings in the austral summer and spring during La Niña events.3. Depth was the most important predictive variable for spatial distribution of whale sharks, followed by chlorophyll-a. Sharks were predicted in shallower coastal waters in which chlorophyll-a values are higher. 4. Habitat suitability was higher in the northern coastal part of the study area. Spring presents the most suitable environmental conditions for whale sharks, both during La Niña and El Niño conditions. The probability of whale shark presence in the north of Peru increases at higher chlorophyll-a and sea surface temperature values. Therefore, whale sharks appear to aggregate seasonally in northern Peru, potentially exploiting rich foraging grounds. 5. In these areas of high suitability, whale sharks are susceptible to fisheries, bycatch, ship collisions, unmanaged tourism, and pollution; thus, management actions should focus in these areas.6. This study represents a first step to understand the distribution and habitat suitability of whale shark in Peruvian waters. Further studies should identify suitable habitat for whale sharks in offshore areas. Also, these should focus on the connectivity of these aggregations with other localities in the south-eastern Pacific in order to contribute to regional strategies for the conservation of this iconic species in this particular region.

Habitat suitability ofRhincodon typusin three localities of the Gulf of California: Environmental drivers of seasonal aggregations

“…The observed climate differences between seasons in the three aggregation sites evidenced the effect of environmental factors on habitat suitability (González‐Pestana et al ., 2020). For instance, in BLA the relative density of whale sharks was related to deep waters and steeper slopes, higher CHLO a concentration and lower SST.…”

“…These records were obtained during multiple scientific or tourist surveys, in which a standardization according to the sampling effort was not possible, thus the records of occurrence were driven by the different sampling efforts in known distribution areas. However, the combination of records, along with environmental factors, were useful for the description of the habitat suitability of whale sharks as it has been proved in other studies (González‐Pestana et al ., 2020; Melo‐Merino et al ., 2020). Once the database of historical occurrences was generated, the sightings were processed with a single sightings record considered for every 1 km 2 to decrease spatial autocorrelation (Radosavljevic & Anderson, 2014) which was included in a geographic information system QGIS v.3.4.4.…”

“…In the Eastern Tropical Pacific, seasonal aggregations of whale sharks occur in the northern coast of Peru, the Galapagos Islands in Ecuador and the Gulf of California in Mexico, where differences between movements, sex ratios and size of the sharks have been observed (González‐Pestana et al ., 2020;Ketchum et al ., 2013; Whitehead et al ., 2019b). In the Gulf of California, whale sharks occur seasonally from October through March in Bahía de La Paz (Ketchum et al ., 2013; Whitehead et al ., 2019b), May to November in Bahia de Los Angeles (Ramírez‐Macías et al ., 2012) and November to March in Nayarit (Ramírez‐Macías et al ., 2015).…”

Setting Conservation Priorities for Marine Sharks in China and the Association of Southeast Asian Nations (ASEAN) Seas: What Are the Benefits of a 30% Conservation Target?

“…Primary productivity is also an important factor that affects shark distribution and abundance (MacKenzie et al, 2019). Many studies have widely demonstrated the relationship between the primary productivity and fisheries catch (Pauly and Christensen, 1995;Watson et al, 2014), and primary productivity variability is significantly and positively correlated to the mean trophic level of catches (Conti and Scardi, 2010); therefore, the primary productivity is used in most SDMs (Gonzalez-Pestana et al, 2020;Chan et al, 2021). Other environmental variables like depth, dissolved oxygen, salinity, and offshore distance are often used in the study of marine shark distribution (Sequeira et al, 2014;Meyers et al, 2017;Chan et al, 2021;Pottie et al, 2021;Gonzaĺez-Andreś et al, 2021).…”

“…The potential distribution of the whale shark (R. typus) was the most extensive in the present study area. The whale shark is a filter-feeding shark with global distribution in tropical and warm temperate regions that fed on zooplankton (Pierce and Norman, 2016;Gonzalez-Pestana et al, 2020). The scalloped hammerhead (S. lewini) is also distributed in warm temperate and tropical seas and frequently occurs in the southern South China Sea and the southern Gulf of Mexico.…”