Date: August 15th, 8:00am
Today's fish of the day is the golden trout!
The golden trout, sometimes called the California golden trout, scientific name Oncorhynchus mykiss aguabonita, is a subspecies of rainbow trout, and the state freshwater fish of California! Found in and around the Sierra Nevada mountains, this trout is native to the South Fork Kern river and golden trout creek. Originally these rivers were disconnected from the larger Kern river, allowing the golden trout to evolve alone and isolated from other salmonids. However, volcanic activity connected these rivers into a larger connected system, causing great threat to the golden trout as threats of hybridization with the cutthroat trout of the area. These golden trout thrive best in areas with deep pools, ample aquatic vegetation to hide within, and streamside cover. The golden trout is best known for their impressive elevations, being found naturally from 2,100-3,000 meters above sea level in their native range, but can be found stocked and thriving at elevations of 3,000-4,000m.
Like all salmonids, these fish are known for feeding on invertebrates, particularly various flies, crustaceans, larvae, and other assorted zooplankton. This diet allows them to get to a respectable size of 6-12 inches in rivers and other bodies of moving water, however there are recorded golden trout of 16-18 inches in lakes. Golden trout are closely related to two other subspecies of rainbow trout also found in and around the Kern river and the Sierra Nevada mountain range. Those being the little Kern golden trout (Oncorhynchus mykiss whitei), and the Kern river rainbow trout (Oncorhynchus mykiss gilberti) respectively. These subspecies are visually distinct with another, although there is significant cross breeding between the three and other trout, threatening their populations. The golden trout in particular can be identified by the distinct golden flank, red horizontal bands along the lateral line, and 10 dark parr marks on each side. This is distinct from the other rainbow trout subspecies, as the little Kern golden trout has greater spotting patterns along the back, as well as darker coloration, and a smaller maximum size. The Kern river rainbow trout are much closer in coloration to the average stocked rainbow trout, although this may be due to extensive hybridization, making it distinctive from the golden trout.
(pictured above, golden trout, Oncorhynchus mykiss aguabonita)
(pictured above, little Kern golden trout, Oncorhynchus mykiss whitei).
(pictured above, Kern river rainbow trout, Oncorhynchus mykiss gilberti)
Spawning season in these fish, as all salmonids, takes place between May-August, with the golden trout laying in the late June to early July. Unlike many other salmonids, these fish have a minimal migration. The golden trout will travel only within 10km in search of an appropriate area to lay. These fish search for areas of fine gravel, with little to no collected algaes on them, and slight oxygenated flow of water, dispersing fertilized eggs within the gravel, before adults will leave the breeding grounds. These eggs will hatch within 3 weeks, and the fry will spend another 2-3 weeks feeding on zooplankton before emerging from the gravel and beginning to feed on insect larvae. Within the first three years of their lives, these fish will grow to a size of 6-8 inches before becoming sexually mature and beginning to migrate toward their stream of birth, although not always spawning there. After this, these trout can live 6-7 years, with some in their natural habitat living as long as 9 before passing.
That's the golden trout! Have a wonderful day!
Sources:
“Utah Natural Heritage Program.”Species Database - Utah Natural Heritage Program Field Guide,fieldguide.wildlife.utah.gov/?species=oncorhynchus+mykiss+aguabonita.
“Conservation.”CDFW,wildlife.ca.gov/Conservation/Fishes/California-Golden-Trout.
“California Golden Trout.” NatureServe Explorer 2.0,explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.101620/Oncorhynchus_mykiss_aguabonita.
“Golden Trout.”Washington Department of Fish & Wildlife, wdfw.wa.gov/species-habitats/species/oncorhynchus-mykiss-aguabonita.