Sal­mon don’t grow on trees

The Press - Escape - - FISHING - Peter Shutt

Re­leas­ing sal­mon fry into the wild has be­come com­mon­place, but at East Coast South Is­land sal­mon hatch­eries op­er­a­tions, a strong ef­fort to in­crease the com­mon sense and sci­ence of the oper­a­tion is in place.

The par­ents are har­vested with great care and the cap­ture of eggs and milt is to a planned timetable. The re­sults make it all worth­while.

Sal­mon runs in East Coast rivers re­sulted from sal­mon re­leases from the govern­ment hatch­ery orig­i­nally es­tab­lished on the Hakataramea River. Since about 1901, sal­mon have ranged widely, helped by hatch­ery re­leases in Dunedin, Cen­tral South Is­land, and North Can­ter­bury.

The sur­prise es­tab­lish­ment of sal­mon in Otago Har­bour re­sulted from a suc­cess­ful re­lease made by the late Ron Dougherty, through the gen­eros­ity of MAF. To­day, Otago Har­bour is a proud sal­mon fish­ery that ex­tends right into the cen­tre of Dunedin – rightly known as Sal­mon City of the South­ern Hemi­sphere.

Re­cently 21,700 smolt were re­leased into the Leith River, with the over­all re­lease this cal­en­dar year of about 58,700 smolt. A fur­ther re­lease of about 45,000 smolt from the Dunedin City Sal­mon Trust hatch­ery was made by the Otago Sal­mon An­glers As­so­ci­a­tion last week.

The re­cent re­lease of 60,000 sal­mon smolt from McKin­non’s Creek hatch­ery (on the Ran­gi­tata River) is a good ex­am­ple of how hatch­ery prac­tices are gain­ing im­proved re­sults.

Three weeks ago I saw a re­lease and ded­i­cated hatch­ery vol­un­teer Bill Whipp showed me a race­way con­tain­ing 35,000 of the 100gsmolt.

‘‘We have found this to be the man­age­able ca­pac­ity in this race­way. They didn’t do as well last year when we had more smolt,’’ he says.

The daily in­spec­tion of smolt in the race­ways has helped main­tain the health of these small fish.

‘‘We run a tight pro­gramme and all the hatch­ery vol­un­teers are vig­i­lant to en­sure smolt health.

‘‘From the cap­ture of adult male and fe­male sal­mon, we strip eggs and milt and fer­tilise the eggs on day one,’’ he ex­plains. ‘‘Af­ter 15 days they eye up, al­though this may de­pend upon wa­ter tem­per­a­ture and at some hatch­eries the eyed-up con­di­tion is known to take as many as 30 days.’’

Through­out this time dead eggs are re­moved from the trays con­tain­ing tens of thou­sands of eggs, and for about 44 days the egg sac nour­ishes the alevin as it slowly de­vel­ops into a small fish.

If the eggs were hatch­ing in the wild, these small fish would find them­selves sub­merged be­neath many cen­time­tres of shin­gle – the pro­tec­tive cov­er­ing their par­ents pro­vided over the redd – but in the hatch­ery en­vi­ron­ment they face lit­tle ef­fort to reach sur­face wa­ter.

Bill Whipp says the hatch­ery achieved 95 per cent egg fer­til­i­sa­tion this year and has shared this bounty, in­clud­ing 170,000 eggs go­ing to Me­sopotamia.

A suc­cess­ful hatch­ery de­mands care­ful ob­ser­va­tion and at­ten­tion through­out the egg stage; a reg­u­lar feed­ing pro­gramme of qual­ity feed there­after, wa­ter qual­ity con­sid­er­a­tion, and gen­tle han­dling that avoids stress­ing the fish.

In North Can­ter­bury, re­leases have come from hatch­eries at Mon­trose (on the up­per Rakaia River), Pea­cock Springs (in Isaacs Quarry on the south side of the Waimakariri River) and Sil­ver­stream (north side of Waimakariri River).

North Can­ter­bury Fish and Game has re­leased 60,000 smolt into the Waimakariri River and 60,000 smolt into the Rakaia River.

A huge ef­fort by the New Zealand Sal­mon An­glers As­so­ci­a­tion and the Rakaia River Fish­ing Pro­mo­tions team and vol­un­teers has seen a very sig­nif­i­cant num­ber of sal­mon eggs im­planted in the re­gion.

I un­der­stand some 400,000 eggs have been im­planted in Scotty boxes, in­cu­ba­tors, alev­ina­tors, and through bar­rel plant­ing. This is where the streambed is ex­ca­vated a short dis­tance and a bar­rel placed ver­ti­cally over the site. About 2000-3000 sal­mon eggs are placed into the still wa­ter within the de­pres­sion and shin­gle heaped over the site to cre­ate an ar­ti­fi­cial redd.

About 250,000 eggs were planted in the up­per reaches of the Waimakariri and Hu­runui Rivers, and 150,000 eggs went in the up­per reaches of the Rakaia River.

Con­sid­er­ing some­thing like 3000 an­glers a week fish be­low the old Waimakariri Bridge and in the river mouth for sal­mon, and that 20 per cent of this sea­son’s Waimakariri catch were fin­clipped fish, it sug­gests these fish ben­e­fited an­glers be­fore wild fish re­turn­ing as well as aug­ment­ing the whole sea­son.

‘‘With­out these hatch­ery re­leases and the ova plant­ing en­hance­ment, wild sal­mon re­turns could have been as low as 30 per cent of cur­rent re­turns,’’ says Ron Stu­art, a keen sal­mon an­gler of 30 years, and a for­mer pres­i­dent of the as­so­ci­a­tion. He leads the sal­mon en­hance­ment ac­tiv­i­ties.

Stu­art says ear­lier this year a team from the as­so­ci­a­tion wa­terblasted a 50m sec­tion of the bed of Hack­etts Stream and dur­ing the spawn­ing sea­son it at­tracted nine nat­u­ral sal­mon redds.

Also on this stream, the as­so­ci­a­tion has es­tab­lished a large alev­ina­tor with ap­prox­i­mately 40,000 sal­mon ova in tra­di­tional Scotty boxes, and says an­glers are grate­ful to the property own­ers through which this stream runs, for their co-oper­a­tion and sup­port for the sal­mon fish­ery.’’

So next time you think about sal­mon, think about the few who do so much to en­sure the sal­mon re­source is there for Otago, Cen­tral South Is­land, and North Can­ter­bury an­glers. It’s three re­gions work­ing to­gether for the com­mon goal . . . more sal­mon in the rivers and har­bour.

The re­ward: Brett Bense­mann with a limit bag of sal­mon from Dunedin Har­bour.

Photo: RONSTUART

Fish plant­ing: Vol­un­teers use bar­rels to cre­ate pro­tected sal­mon redds in North Can­ter­bury.

Photo: RONSTUART

Nurs­ery: In­cu­ba­tors in se­quence in North Can­ter­bury spawn­ing wa­ter.

Photo: PETER SHUTT

Feed­ing out: Keen vol­un­teer Bill Whipp looks af­ter smolt in the race­way on the Ran­gi­tata River.

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