Spawning densities, egg densities, size structure, and movement patterns of spawning horseshoe crabs,Limulus polyphemus, within four coastal embayments on Cape Cod, Massachusetts

Conservation status of the American horseshoe crab, (Limulus polyphemus): a regional assessment

“…Some observations suggest that horseshoe crabs prefer to spawn around the time of the new and full moon high tides, which are the highest tides of the month (Rudloe 1980;Brockmann 2003b;Barlow et al 1986;Brockmann and Johnson 2011;Smith et al 2002b, Chabot et al 2008Watson and Chabot 2010). However, other studies have reported that the association between spawning activity and the lunar period is not strong or only slightly higher than expected by chance alone Cheng et al 2016) and that spawning occurs at a similar intensity during all daytime high tides regardless of lunar phase (James-Pirri et al 2005;Leschen et al 2006). In some areas horseshoe crabs seem to prefer the higher of the two daily tides regardless of light:dark cycle (Barlow et al 1986;Rudloe 1980;Chabot and Watson 2010;Brockmann and Johnson 2011).…”

“…At the northern end of their range, horseshoe crabs breed in May and June, moving up the estuaries in which they overwinter as the water warms (Cheng et al 2015;Moore and Perrin 2007;Schaller et al 2010). In Cape Cod, Massachusetts, spawning occurs from May through July with peaks in May and June (Barlow et al 1986;Widener and Barlow 1999;James-Pirri et al 2005). In Long Island Sound, spawning begins in early May and peaks by the end of May (Beekey and Mattei 2009).…”

“…Unattached males return to the beach more frequently than females, creating male-biased OSR and male-male competition for mates (Rudloe 1980;Brockmann 1990;Smith et al 2002aSmith et al , 2010Brockmann and Smith 2009;Brockmann and Johnson 2011). The mean OSR in unharvested populations is generally 1.5-2.4 males to females (Rudloe 1980;Wenner and Thompson 2000;Schaller 2002;Brockmann and Johnson 2011), but in populations with female-biased harvest the sex ratio is elevated, i.e., 3 to 8 males/female (Smith et al 2002b(Smith et al , 2009aCarmichael et al 2003;James-Pirri et al 2005;Kreamer and Michels 2009). Mean OSR during the 2012-2013 spawning season in Chuburná, Yucatán, was 1.1 males to females (unpublished data, J. Gutiérrez and J. Zaldívar-Rae, Anáhuac Mayab University).…”

“…Along the Mid-Altantic coast, many populations migrate to the ocean. While the greatest proportion of the Delaware Bay horseshoe crabs appear to migrate to the continental shelf (Botton and Ropes 1987;Hata and Hallerman 2008), tagging data indicate that some Delaware Bay crabs and most crabs across the New England States remain within local regions and overwinter in local embayments (Botton and Ropes 1987;James-Pirri et al 2005;Swan 2005;Moore and Perrin 2007;Beekey and Mattei 2009;Schaller et al 2010;Beekey and Mattei 2015). Landi et al (2015) found that spawning beach locations within Long Island Sound tended to be those closer to offshore locations where adults were caught in trawl surveys.…”

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“…En cada transecto, se seleccionaron tres cuadrantes de 1m 2 (nombrados a, b y c), medidos en forma alternada entre la línea de marea alta y baja, respectivamente (Rosales-Raya, 1999). En cada cuadrante se cavó con una pala hasta una profundidad de 40 cm, se Numerous studies have been conducted in order to describe the spawning and reproduction patterns of L. polyphemus in the USA (Botton and Loveland, 1989;Brockmann, 1990;Penn and Brockmann, 1994;Smith et al, 2002;James-Pirri et al, 2005;Botton and Loveland, 2011). …”