Can we bolster the recovery of summer chum through hatchery supplementation?
Hood Canal summer chum were nearly extinct by the early 1990s. In response, state and tribal co-managers created the Hood Canal Summer Chum Salmon Conservation Initiative. Since 1998, LLTK has contributed to this initiative by operating a conservation hatchery program to increase the abundance of naturally spawning summer chum in Lilliwaup Creek and the Hamma Hamma River. The work has been a major success, increasing the number of adults returning to these rivers annually from the low 100s to well over 2,000.
The number of Hood Canal summer chum declined from over 10,000 returning adults in the 1970s to less than 1,000 in the 1990s. Some Hood Canal summer chum populations were extirpated and the risk of extinction for several others was high.
By the late 1990s resource managers began taking actions to curb over harvest, and work to restore habitat began. With the abundance of some summer chum populations critically low and other populations extirpated, resource managers looked to hatchery rearing. They surmised that hatchery rearing could be used to re-introduce and/or boost the populations in greatest need while habitat and harvest limiting factors were being addressed. This would be limited intervention: long enough to boost the population to a point where they are again self-sustaining, but short enough to prevent a reduction in genetic fitness that can be associated with hatchery production.
In 1998, LLTK worked with state and tribal partners to initiate a conservation hatchery program to increase the abundance of naturally spawning summer chum in Lilliwaup Creek and the Hamma Hamma River. Overall, the summer chum recovery projects have been a great success. In the Hamma Hamma River, we discontinued operations after successfully making the population self-sustaining: adult returns have risen from ~100 in the 1990s to an average of 1,849 (2005-2015). In Lilliwaup Creek, the number of adult chum returning to spawn has risen from 15 to 20 per year in the 1990s to an average of 1,092 per year (2006-2015).
Summer chum populations saved
chum returning annually
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Je, tunaweza kuimarisha kupona kwa samaki wa majira ya kiangazi kwa kutumia virutubisho vya kiwanda cha kuzalisha? Mnyama huyo wa kiangazi wa Hood Canal alikuwa karibu kutoweka mapema miaka ya 1990. Kwa kujibu, wasimamizi wa jimbo na makabila waliunda Mpango wa Uhifadhi wa Salmon wa Chum wa Majira ya joto wa Hood Canal. Tangu mwaka 1998, LLTK imeshiriki katika mpango huu kwa kuendesha mpango wa kuhifadhi hatchery ili kuongeza wingi wa chum ya majira ya joto ya asili katika Lilliwaup Creek na Mto Hamma. Kazi hiyo imefanikiwa sana, na kuongeza idadi ya watu wazima wanaorudi kwenye mito hiyo kila mwaka kutoka chini ya 100 hadi zaidi ya 2,000. Idadi ya ndege wa majira ya joto wa Hood Canal ilipungua kutoka zaidi ya 10,000 waliorudi katika miaka ya 1970 hadi chini ya 1,000 katika miaka ya 1990. Baadhi ya idadi ya chum ya majira ya joto ya Mfereji wa Hood iliondolewa na hatari ya kutoweka kwa wengine kadhaa ilikuwa kubwa. Kufikia mwishoni mwa miaka ya 1990, wasimamizi wa rasilimali walianza kuchukua hatua za kuzuia mavuno ya kupita kiasi, na kazi ya kurudisha makazi ilianza. Kwa kuwa idadi ya wanyama fulani wa majira ya kiangazi ilikuwa chini sana na wengine walikuwa wameangamizwa, wasimamizi wa mali za asili walitafuta njia ya kuwafuga wanyama hao. Walitambua kwamba ufugaji wa hatchery unaweza kutumika kuanzisha tena na au kuongeza idadi ya watu wenye uhitaji mkubwa wakati mazingira na sababu za kupunguza mavuno zilikuwa zikishughulikiwa. Hii itakuwa ni hatua ndogo: muda wa kutosha kuongeza idadi ya watu hadi hatua ambapo wao ni tena kujitegemea, lakini muda mfupi wa kutosha kuzuia kupunguzwa kwa uwezo wa maumbile ambayo inaweza kuhusishwa na uzalishaji wa hatchery. Mwaka 1998, LLTK ilifanya kazi na washirika wa serikali na makabila kuanzisha mpango wa kuhifadhi hatchery ili kuongeza wingi wa chum wa majira ya joto katika Lilliwaup Creek na Mto Hamma. Kwa ujumla, miradi ya kupona ya chum ya majira ya joto imekuwa na mafanikio makubwa. Katika Mto Hamma, tumeacha shughuli baada ya kufanikiwa kufanya idadi ya watu kujitegemea: kurudi kwa watu wazima kumepanda kutoka ~ 100 katika miaka ya 1990 hadi wastani wa 1,849 (2005-2015). Katika Lilliwaup Creek, idadi ya chum wazima kurudi kuzaa imeongezeka kutoka 15 hadi 20 kwa mwaka katika miaka ya 1990 hadi wastani wa 1,092 kwa mwaka (2006-2015). Miongoni mwa watu waliokamatwa na kuuawa kwa miaka miwili ni: (a) Mkurugenzi wa Shirika la Usalama wa Jamii (mwenye jina la kwanza, jina la mwisho, na jina la mwisho)