Unusual record of Pacific harbor seal ( Phoca vitulina richardii ) feeding on anchovy ( Engraulis mordax ) in the fishery of small pelagic fishes in the Gulf of California Registro inusual de la foca común ( Phoca vitulina richardii ) alimentándose de anchoveta ( Engraulis mordax ) en la pesquería d

Pacific harbor seals (Phoca vitulina richardii) range in North America from Japan to Mexico. Here we report the first record of a Pacific harbor seal feeding on Northern anchovy (Engraulis mordax) inside a purse-seine net of a sardine fishing boat in the Gulf of California. This event was recorded on video on January 11th, 2010, near Estero Tortuga, Guasimas, Sonora (27°50’N, 110°39’W). Sea conditions were of El Niño Southern Oscillation; this record was likely due to El Niño, forcing seals to travel beyond their distribution range in search of alternate foraging areas.

In a study of stable δ 15 N and δ 13 C isotopes from hair of Pacific harbor seal pups from Isla Natividad, Baja California, the values obtained indicate that harbor seals do not migrate, clearly showing that harbor seal females display coastal habits on that island (Elorriaga-Verplancken et al. 2016).Pacific harbor seals are capable of moving across long distances searching for foraging or reproductive areas (Hardee 2008).Satellite-instrumented males performed long-distance movements with a mean distance of 103.5 km (range 9.6-280.9km, n= 16), while females traveled an average of 22.9 km (range 6.0-41.6 km, n= 4) (Peterson et al. 2012).Some records of this species show that they can occasionally travel across long distances of up to 520 km (Lesage et al. 2004), and 880 km (Gallo-Reynoso et al. 2010).
The video was sent to the Ecophysiology Laboratory at Centro de Investigación en Alimentación y Desarrollo, A.C. Unidad Guaymas, requesting an identification of the species of seal found inside the purse.The program Video to Picture Image Converter was used to convert the video to images, aiming at observing and determining the pinniped species involved in this fishing event.

Results and discussion
First record of the Pacific harbor seal feeding in the Gulf of California This paper reports a record of a Pacific harbor seal feeding opportunistically in the Gulf of California.On 11 January 2010, an individual was video-recorded near Estero Tortuga, Las Guásimas, Sonora, Mexico.The individual corresponded to a Pacific harbor seal adult that was feeding on Northern anchovy (Engraulis mordax) inside the purse-seine net of a fishing boat (Fig. 1).The species was determined based on the following characteristics: body relatively compact with short front and hind flippers, head rounded, color gray with light spots on the back, nostrils with a distinctive V-shape (Teilmann & Galatius 2018).
There are five previous records of Pacific harbor seals in the Gulf of California: Los Frailes and Los Islotes, in Baja California Sur (Gallo-Reynoso & Aurioles-Gamboa 1984, Sex, body size, local habitat conditions and environmental factors have an influence on the pattern and range of foraging of harbor seals (Thompson et al. 1988, Peterson et al. 2012, Sharples et al. 2012, Blanchet et al. 2014).When the video of the harbor seal was recorded in winter of 2010 on the coast of Sonora, the conditions at sea were typical of El Niño Southern Oscillation that lasted from June 2009 to May 2010 (Todd et al. 2011).The coast where the seal was found is nutrient-rich due to fresh water runoff during summer and coastal upwelling during winter-spring (Soto-Mardones et al. 1999); this suggests that the individual observed was likely present because the estuary is rich in fish and small squid species, being intensively used by California sea lions (Zalophus californianus) as feeding grounds in winter and spring.

Main prey of the Pacific harbor seal in Mexico: opportunistic feeding of anchovy in the Gulf of California
There are few studies on the foraging habits of Pacific harbor seals in Mexico.The main prey types consumed included fish of the families Paralichthyidae, Synodontidae, Achiridae, Belonidae, Clupeidae, Sebastidae, Ophidiidae, Batrachoididae, and Cottidae, and cephalopods of the families Octopodidae and Loliginidae (Table 1)  In all these studies (Table 1), the foraging habits of seals were explored by sieving scats and identifying otoliths and cephalopod beaks, although this methodology could not yield the complete trophic spectrum; hence, other methodological approaches such as metagenomics, fatty acids and stable isotopes from scats and other tissue samples should also be applied to explain the foraging habits of seals (Bromaghin et al. 2013, Elorriaga-Verplancken et al. 2013, Brassea-Pérez 2016).
The Northern anchovy (Engraulis mordax) is not a major prey item for the Pacific harbor seal in Mexico (Table 1); however, it is an important prey in some areas of the United States, such as San Francisco Bay, California (Gibble & Harvey 2015), San Juan Islands, and Drayton Harbor, Washington (Lance et al. 2012, Luxa & Acevedo-Gutiérrez Table 1.Main prey types of the Pacific harbor seal in Mexico according to the prey importance index (≥ 10% IIMPi) obtained by different authors / Principales presas de la foca común en México de acuerdo al índice de importancia de presa (≥ 10 % IIMPi) 2013).Northern anchovy occupies an important niche in the marine trophic web, and also plays a central ecological and fishery role in the California Current and the Gulf of California (Cotero-Altamirano 2000).The large variety of prey species and the regional differences are indicative of an opportunistic foraging behavior of the Pacific harbor seal (Steingass 2017).
In conclusion, this record of a Pacific harbor seal in the Gulf of California contributes new information on the distribution of this subspecies and likely use of areas for foraging outside its reproductive range, and illustrates new aspects of its interaction with fisheries.In addition, this record adds to the knowledge of this top predator under peculiar oceanographic conditions such as El Niño 2009-2010.