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Patterns of Growth in Fishes

Patterns of Growth in Fishes. Grow and Survive to Reproduce. Growth patterns in fishes. Context for study of growth: to “succeed”, a fish must reproduce viable offspring to reproduce, a fish must survive long enough to reach maturity to reach maturity, a fish must grow:.

gwendolyn-fuller
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Patterns of Growth in Fishes

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  1. Patterns of Growth in Fishes Grow and Survive to Reproduce

  2. Growth patterns in fishes • Context for study of growth: • to “succeed”, a fish must reproduce viable offspring • to reproduce, a fish must survive long enough to reach maturity • to reach maturity, a fish must grow:

  3. Factors Affecting Growth • Hormones– Growth hormone secreted by pituitary – Steroid hormones from gonads • Temperature– Most important environmental factor – Growth increases up to a point – Fish tend to prefer temperatures where their growth is maximal

  4. Growth patterns in fishes • Dissolved Oxygen– More is better • Ammonia– High concentrations slow growth • Salinity– Growth is altered when fish are not in their optimum salinity

  5. Growth patterns in fishes • Competition – Generally slows growth • Food– Availability & quality affect growth • Photoperiod– Longer days increase growth

  6. Growth patterns in fishes • • Age & Maturity– Growth is rapid early in life – With maturity more energy is diverted to gonadal tissue – Larger fish need more energy to maintain body • Conditioning(Weight lifting for fish??)

  7. Keys to success: • GROW • SURVIVE • REPRODUCE

  8. Bioenergetic context • Growth is the accumulation of somatic (body) tissue that depends on a surplus of energy consumed

  9. Bioenergetic context • Bioenergetic equation: • I = M + G + R + E • I = energy ingested • M = energy used to maintain healthy tissues • G = energy for growing somatic tissue • R = energy for reproduction • E = energy “lost” through inefficiency of energy transfers, etc.

  10. Growth Rate • Anything in the internal or external environment that increases or decreases I: • food availability • competition with other fish for food • time spent hiding from or escaping predators • time spent defending a territory

  11. Growth Rate • Anything in the internal or external environment that increases or decreases M: • temperature • dissolved oxygen • toxins - NH4+, heavy metals, organic toxins

  12. Growth Rate • Energy for growth is a tradeoff with energy for reproduction • general pattern: grow first, then reproduce • increased size --> • increased fecundity (females) • increased territorial success (males, females) • increased metabolic efficiency (to a point)

  13. Fish growth often is periodic • Seasonal variation in temperature, food availability, spawning activity, can cause seasonal growth cessation (Can you think of examples where this might happen?)

  14. Fish growth often is periodic • Seasonal variation in temperature, food availability, spawning activity, can cause seasonal growth cessation • If periods are regular (e.g., annual or daily), a record of growth and no-growth periods is formed in hard structures: • scales, fin spines or rays, vertebral centra, opercle bones, ear bones (otoliths)

  15. Fish growth often is periodic • Periodic growth marks allow estimation of growth rates by counting and measuring distances between growth checks

  16. Endocrine Growth Regulation • Pituitary growth hormone: • increases appetite • increases food conversion efficiency • increases production of stomatomedin (stimulate cell growth and division)

  17. How do different forms of mortality effect overall population growth??

  18. Internal regulation of growth - endocrine system • Anabolic steriods stimulate growth: • testosterone in males • estrogen in females • corticosteroids in both sexes

  19. Internal regulation of growth - endocrine system • Thyroid hormones stimulate growth • Also regulate metamorphosis

  20. Fish growth is indeterminate • Growth continues throughout life cycle • limits to ultimate size are BIOTIC (food availability, metabolic efficiency) and not MECHANICAL (counteracting gravity, etc.)

  21. Fish growth is indeterminate • Advantages to indeterminate growth: • larger size yields greater efficiency

  22. Fish growth is indeterminate • Advantages to indeterminate growth: • larger size yields greater efficiency • larger size yields more food options • faster swimming • larger gape size • better sensory range & acuity

  23. Fish growth is indeterminate • Advantages to indeterminate growth: • larger size yields greater efficiency • larger size yields more food options • larger size reduces number of potential predators • swimming speed • gape size

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