Ch. 3 Pacific Salmon Migration in a Dynamic Ocean

Oncorhynchus nerka Sockeye, Red, Blueback A smaller species, averaging about six pounds, sockeye typically rear for 1 or 2 years in lakes prior to migrating to sea. The fish mature after 2 or 3 years at sea.

contents Commentary: 3.1 Introduction 3.2 Phases in migration 3.3 Phase 1: directed coastal migration 3.4 Phase 2: open ocean migration 3.5 Phase 3: directed migration to the coast 3.6 Phase 4: directed coastal migration to natal stream 3.7 Conclusions Commentary:

3.1 Introduction Seasonal and life stage related migrations of fishes Speculations about the cues and clues that stimulate and direct these migrations The relationship between migratory behavior and the dynamic ocean environment High economic value – sustainable exploitation Salmon possess a remarkable set of capabilities Finding and maintaining a direction of migration Distinguishing between water masses smell, salinity, temperature or order Sun, star Earth’s magnetic field Other compass direction cue [kjuː] n. 〖연극〗 큐(대사의 마지막 말; 다음 배우 등장 또는 연기의 신호가 됨); 〖음악〗 (연주의) 지시 악절(樂節); 단서, 신호, 계기, 실마리; 역할, 구실; (고어) 기분. ♣give a person the [his] ∼ 아무에게 암시[힌트]를 주다, 귀띔해 주다. ♣in the ∼ for (walking) (산책)하고 싶은 기분이 나서. ♣on ∼ 마침내 좋은 때에, 적시에. ♣take the [one's] ∼ from ┅에서 단서를 얻다, ┅을 본받다. cue [kjuː] v. (cu(e)ing) ―vt. ┅에게 신호[지시]하다; 〖연극〗 ┅에게 큐를 주다; 〖음악〗 (┅에) 큐를 넣다(in; into); (음·효과 따위를) 삽입하다(in). ―vi. 〖영화〗 촬영 개시의 신호를 내다. ♣∼ a person in 아무에게 큐[신호]를 보내다[주다]; (비유) 아무에게 ┅에 관해서 알리다(on). cue n. 변발(辮髮)(queue); ; (차례를 기다리는 사람의) 줄(queue); 〖당구〗 큐. cue v. (cú(e)ing) ―vt. (머리 따위를) 땋다, 틀다(twist); 큐로 치다. ―vi. 열지어 늘어서다(up); 큐로 치다(on). clue [kluː] n. ① (수수께끼를 푸는) 실마리, (십자말풀이의) 열쇠, (조사·연구의) 단서. ② 이야기의 줄거리, 사색의 실마리. ③ (미궁에의) 길잡이. ④ (미국속어) 정보, 개인적인 의견. [cf.] clew. ♣get a ∼ (1) 실마리를 얻다; (미국구어) 실정을 잘 보다, 깨닫다, 꾀발라지다. (2) (미국속어) 이해되다, 알다. ♣not have a ∼ (구어) 어림이 안 잡히다, (구어) 무지[무능]하다. clue [kluː] vt. 암시로 보여주다, (구어) ┅에게 단서를 주다, (미국속어) 털어놓다; =CLEW. ♣∼ a person in [up] (속어) 아무에게 단서를 주다, 알리다, 설명하다. ㉺∼less [-lis] ―a. 단서 없는; (구어) 어리석은, 무지한. 신호와 실마리 자극해서 인도

How they employ those capabilities during migration 3.1 Introduction How they employ those capabilities during migration The role that migration plays in the ecology of salmon In the decision rules that govern migration behavior A descriptive to a functional analysis of the influence of ocean Relationships between ocean dynamics and salmon migration Salmon migration and the dynamics of the North Pacific Ocean A set of behavior rules: growth, survival and reproduction ‡stimulate [stímjəlèit] v. ―vt. ① 『∼+목/ +목+to do/ +목+전+명』 자극하다, 활발하게 하다; 북돋우다(incite); 격려[고무]하다; ┅의 격려가 되다. ② (커피·주류 따위로) 흥분시키다; 〖의학·생리〗 (기관(器官) 따위를) 자극하다. ―vi. 자극[유인]이 되다, 격려가 되다; 술을 마시다. ┈┈•High wages ∼s the national economy. 높은 임금이 국가의 경제를 자극했다.―vt. ① ┈┈•Praise ∼d students to work harder. 칭찬에 자극되어 학생들은 더 열심히 공부하게 됐다. ┈┈•∼ a student's interest in poetry 시에 대한 흥미를 자극하다. 행동 성장 - 생존 - 번식

Sockeye salmon from the Fraser River in BC 3.2 Phases in migration Four phases: Coarse scale differences in behavior Sockeye salmon from the Fraser River in BC Phase 1: directed coastal migration Phase 2: open ocean migration Phase 3: directed migration to the coast Phase 4: directed coastal migration to natal stream Three inter-related ecological problems

3.2 Phases in migration Phase 1: directed coastal migration From late April through May each year Yearling smolts → leave freshwater nursery lakes → enter the marine waters of the Strait of Georgia Throughout the summer and autumn; Migrate north and west along the coast of the vicinity of Kodiak Island Phase 2: open ocean migration Winter or the following spring Move south into the Gulf of Alaska Remain for about 18 months; Offshore feeding phase Phase 3: directed migration to the coast Spring (May, June) following the second winter in the ocean 4-years-old Directed migration back to coastal waters; Oceanic migration Phase 4: directed coastal migration to natal stream Seek out the Fraser River; Begin their upstream migration

Three inter-related ecological problems Accumulate lots of surplus energy for growth and maturation; Survive; and Get positioned geographically to do well in the next phase

Phase 1: directed coastal migration All of the smolts moved north along the east side of the strait and exited via Johnstone Strait 6-7 km∙d-1 (7-8 cm∙s-1) The surface circulation of the Strait of Georgia during April to June Passive drift with prevailing currents as the fish devote their attention to efficient foraging

Phase 1: directed coastal migration The rules Maximize net energy accumulation by feeding actively and minimizing energetic costs of foraging When actively migrating, swim west or northwest Swim away from low salinity water to avoid getting trapped in fjords and deep bays

Phase 2: open ocean migration the Alaskan gyre the eastward flowing subarctic current the northward flowing Alaskan current the westward flowing Alaskan stream the fishes’ primary problem in the open ocean is to find the unpredictable patches with combinations of food and temperature in which good growth can be achieved efficient search behavior rather than directional swimming the trade-off between avoiding predation and accumulating surplus energy general predator avoidance tactics (e.g. cryptic coloration, vigilance, schooling, and burst swimming to evade a predator attack)

Phase 2: open ocean migration The rules governing migration behavior If in a patch that provides for positive growth, stay there If not in a patch that provides for positive growth, search in the most energetically efficient way for one that does Avoid predators

Phase 3: directed migration to the coast In the spring following their second winter Begin their home ward migration as maturing fish 20-30 km∙d-1 continue to grow during this period take advantage of feeding opportunities during their migration back to the coast NDR the Northern Diversion Rate (NDR)

Phase 3: directed migration to the coast The rules governing migration behavior Initiate migration to the coast early so that there will be time to compensate to the unknown distance to the coast and the oceanic conditions that will be met en-route Swim east or southeast at an energetically efficient speed (other stocks would have different directional preferences) Forage opportunistically Avoid predators

Phase 4: directed coastal migration to natal stream Currents are stronger, more variable and less predictable. The rules governing migration behavior Swim south-east at an energetically efficient speed; Avoid predators Avoid low salinity water that dies not smell of home but swim into low salinity water that smells of home Avoid high temperatures Forage opportunistically Three inter-related ecological problems Accumulate surplus energy for growth & maturation (reproduction) Survive (avoid predators) Get positioned for the next stage of migration (or life stage)

Conclusion passive displacement by oceanic currents predator avoidance the movement into offshore waters where food resources are sparse and patchy but predators are probably correspondingly rare objective modeling of migratory behavior in relation to ocean circulation and other oceanic properties how much complexity can be generated by variation in the ocean environment some developing technologies conventional tags and real-time monitoring of fish fitted with ultrasonic tags archival tags that can store information from which to calculate fish positions as well as information on depth and temperature of migration synoptic information on oceanic water properties and circulation derived from remote sensing

Commentary recent example of innovative research programs smart tags sensor technologies smart tags temperature, depth swim speed and geoposition statistical and modeling approaches 3 good reasons to earnestly apply these new sampling and analytical approaches in salmon migration studies: many of the critical physiological and energetic parameters necessary to investigate important ecological phenomena have s strong empirical foundation based on over 40 years of scientific investigations the diversity of different life history patterns expressed in this genus have been well documented salmon are important biologically, economically and culturally and hence deserve our best efforts at conservation potential risks that exist to the sustainability of our salmon populations, including over exploitation, habit destruction, and genetic introgression through hatchery operations and net pen culture occurring worldwide.