On joint spawning of anadromous and resident mykiss Parasalmo mykiss in rivers of Western Kamchatka

Anadromy and residency in steelhead and rainbow trout (Oncorhynchus mykiss): a review of the processes and patterns

“…Anadromous estuarine and half-pounder life histories spend 1-3 years in fresh water and only 1-3 months in estuaries or nearshore areas, respectively, and tend to mature at slightly younger ages and much smaller sizes (250-400 mm in length; Kesner and Barnhart 1972;Kuzishchin et al 2007;Quinn and Myers 2004;Satterthwaite 1988;Savvaitova et al 2002). Residents are typically smaller and younger at maturation than their fully anadromous counterparts, often maturing for the first time at 2-4 years of age and 100-350 mm in length, but, as with anadromy, there is a wide range in size and age at maturation (Behnke 2002;Kuzishchin et al 2007;Schroeder and Smith 1989). Some residents, most commonly males (e.g., McMillan et al 2007), may mature as early as age 1 at very small sizes, whereas others may not mature until ages 5 or 6 at sizes exceeding 800 mm in length Russell 1977;Savvaitova et al 2003;Schroeder and Smith 1989).…”

“…All O. mykiss spawn and rear in fresh water, but in the time between emergence and spawning there is tremendous variation in their migration patterns, age at smolt transformation, and age and size at maturation (Behnke 2002;Kuzishchin et al 2007;Savvaitova et al 2002;Shapovalov and Taft 1954). For example, on the Kamchatka Peninsula, Russia, populations may consist of individuals that spend several years in the open ocean before returning to fresh water for spawning (typical anadromous); others that make nonreproductive migrations to fresh water several months after their initial ocean entry, overwinter there, and then return to the ocean the following spring (half-pounder); others that seasonally enter estuaries repeatedly over successive years before maturing (estuarine) or alternate years between estuaries and rivers throughout their life (river-estuarine); and residents that spend their entire lives in fresh water Savvaitova et al 2003 The various life histories are typically characterized by differences in sizes and ages at maturation.…”

“…Kamchatka; Kuzishchin et al 2007;Savvaitova et al 1997 Resident males matured earlier in life, and at presumably smaller sizes, than resident females Oregon; Christie et al 2011 that all individuals within a population are capable of expressing the full range of alternative tactics (in this case, residency or anadromy; Gross 1996;Hazel et al 1990). The expression of a particular tactic occurs if an individual's condition surpasses a genetically based threshold that triggers one of several alternative developmental pathways (e.g., smolt, mature, wait; Satterthwaite et al 2009).…”

“…For example, on the Kamchatka Peninsula, Russia, populations may consist of individuals that spend several years in the open ocean before returning to fresh water for spawning (typical anadromous); others that make nonreproductive migrations to fresh water several months after their initial ocean entry, overwinter there, and then return to the ocean the following spring (half-pounder); others that seasonally enter estuaries repeatedly over successive years before maturing (estuarine) or alternate years between estuaries and rivers throughout their life (river-estuarine); and residents that spend their entire lives in fresh water Savvaitova et al 2003 The various life histories are typically characterized by differences in sizes and ages at maturation. Fully anadromous individuals spend 1-4 years in fresh water and 1-5 years in the open ocean and generally mature at ages 2-7 and around 500-1100 mm in length (Busby et al 1996;Kuzishchin et al 2007;Quinn and Myers 2004). Anadromous estuarine and half-pounder life histories spend 1-3 years in fresh water and only 1-3 months in estuaries or nearshore areas, respectively, and tend to mature at slightly younger ages and much smaller sizes (250-400 mm in length; Kesner and Barnhart 1972;Kuzishchin et al 2007;Quinn and Myers 2004;Satterthwaite 1988;Savvaitova et al 2002).…”

“…Fully anadromous individuals spend 1-4 years in fresh water and 1-5 years in the open ocean and generally mature at ages 2-7 and around 500-1100 mm in length (Busby et al 1996;Kuzishchin et al 2007;Quinn and Myers 2004). Anadromous estuarine and half-pounder life histories spend 1-3 years in fresh water and only 1-3 months in estuaries or nearshore areas, respectively, and tend to mature at slightly younger ages and much smaller sizes (250-400 mm in length; Kesner and Barnhart 1972;Kuzishchin et al 2007;Quinn and Myers 2004;Satterthwaite 1988;Savvaitova et al 2002). Residents are typically smaller and younger at maturation than their fully anadromous counterparts, often maturing for the first time at 2-4 years of age and 100-350 mm in length, but, as with anadromy, there is a wide range in size and age at maturation (Behnke 2002;Kuzishchin et al 2007;Schroeder and Smith 1989).…”