Increased Juvenile Salmonid Growth by Whole-River Fertilization

Abstract

1990. increased juvenile salmonid growth by wholeriver fertilization. Can. ). Fish. Aquat. Sci. 47: 862-872.Nutrient concentrations, periphyton standing crop and size of steelhead trout (8ncsrhynehus mykiss) and coho salmon (8. kisuteh) fry increased after the fertilization of a nutrient-deficient stream with inorganic phosphorus (P) and nitrogen (N). Wh~le-river fertilimation of the Keogh River, British Columbia, during 4983-86 to increase summer average nutrient csncentrations f r~r n <1 p, g POL-' and 25 pg lal-L-' to 1661 5 pg P-h-' and 30-100 pg N -L -' resulted in five-to 10-fold increases in periphyton standing crops on artificial substrata and 1.4-to 2.0fold Increases in late-September salmsnid fry weights. Diatoms and chlorsphytes dominated the algal periphyton on artificial substrata at fertilized sites. Cyanophytes were unimportant despite low N:P ratios in some cases. juvenile salmonids fed primarily on benthic insects. These results suggest that autochthonous primary production can be an important energy source in forested, middle-order streams, and indicate that the manipulation of autochthonous primary production can be a useful management tool to increase salmonid growth in nutrientpoor coastal streams.Les teneurs en 4l6ments nutritifs, la population exploitable du periphyton et la taille des truites arc-en-eiel (Owcorhywchus mykiss) et des alevins de saurnon coho (0. kisutch) ont augment6 apres fertilisation en pkosphore (P) et azote (N) inorganique d'un cours d'eau pauvre en elements nutritifs. La fertilisation de toute la riviPre Keogh en Colombie-Britannique entre 1983 et 1986, en vue d'accroitre les teneurs estivales moyennes en 6lernents nutritifs de < I pg P-L-' et 25 pg N-L-' a 10-15 p g P.L-' et 30-1 00 pg N-L-' a entraine des augmentations de 5a 10-fsis de la population exploitable du periphyton sur les substrats artificiels et de 1,4-A 2,O-fois dans les poids des aievins de salmonides a %a fin de septembre. Aux sites fertilises, Jes diatom6s et les chlorophyc4es 6taient les plus abondants du p6ripkyton d'algues sur les substrats artificiels. Les cyanophycees 6taient plus nornbreuses malgr6 les rapports N :P faibles dans certains cas. tes satrnonides juveniles se nourrissaient essentiel lernent d'insectes benthiques. Ces r6sultats semblent montrer que la production primaire akitochtogle peut constituer une source 6nergetique importante des cours d'eau moyens, en milieu boise, et indiquent que la manipulation de la production primaire autschtone peut &re un outil de gestion utile en vue d'augmenter la croissance des salmsnides dans des csurs d'eau cdtiers pauvres en Glernents nutritifs.

Water quality, chlorophyll, and periphyton responses to nutrient addition in the Kootenai River, Idaho

“…Investigators also have reported significant increases in salmon production following nutrient addition in nutrient-depleted lakes and streams in British Columbia, Idaho, and Alaska (Johnson et al 1990, Stockner 2003. The effects of reduced nutrient availability and biological production on naturally reproducing anadromous Pacific salmon populations have been described extensively in the literature (Schindler et al 2003, Wipfli et al 2003, Janetski et al 2009), but anthropogenic oligotrophication also has reduced nutrient availability and biological production in rivers and lakes beyond the extent of marine-derived nutrient contributions .…”

Bioenergetic calculations evaluate changes to habitat quality for salmonid fishes in streams treated with salmon carcass analog

“…Whether through the application of liquid agricultural fertilizer, pelletized forms of slow release fertilizer, or even from the addition of sucrose as a source of nutrients, nutrient addition has often led to large increases in stream periphyton and benthic invertebrate abundance (Warren et al 1964;Johnston et al 1990;Slavik et al 2004). Effects on the abundance of salmonids have been detected in the form of increased growth and abundance in some instances (Ward et al 2003), but not others (Wipfli et al 2010;Harvey and Wilzbach 2010).…”

“…In oligotrophic aquatic habitats, the addition of nutrients has produced dramatic increases in primary production as well as their secondary consumers (Johnston et al 1990;Slavik et al 2004). While increases in salmonid fish production have been observed in fertilized lakes (Stockner and MacIsaac 1996), the effect on salmonid production in streams has been equivocal.…”

“…While increases in salmonid fish production have been observed in fertilized lakes (Stockner and MacIsaac 1996), the effect on salmonid production in streams has been equivocal. In some instances inorganic nutrient (Johnston et al 1990), salmon carcass (Bilby et al 1998;Wipfli et al 2003Wipfli et al , 2010, or salmon carcass analog (Kohler et al 2012) addition has led to increases in the growth or abundance of salmonids; whereas in other studies, organic matter and nutrient addition (i.e., salmon carcass) has had little to no effect on salmonid growth or abundance (Wilzbach et al 2005;Harvey and Wilzbach 2010;Cram et al 2011). Furthermore, in instances where increases in salmonid abundance are detected, they are relatively weak in comparison with the increases at lower trophic levels (Grant et al 1998).…”

Declivity in steelhead (<i>Oncorhynchus mykiss</i>) recruitment at the Keogh River over the past decade

“…The watershed, more fully described in Ward and Slaney (1979), Irvine and Ward (1989), and Johnston et al (1990), is in the coastal western hemlock biogeoclimatic zone, with mean annual discharge of 5.3 m 3 ·s -1 and an estimated winter maximum of 254 m 3 ·s -1 . The Keogh River fish fence is situated 300 m upstream from the river mouth, at approximately the high tide mark, and has permitted virtually complete enumeration of downstream-migrant fish during spring, and accurate estimates of the steelhead spawners migrating upstream, since 1976.…”