Resumen del libro siddharta

Fish

CONTENTS
7.1 Introduction 7.2 Species Composition and Distribution 7.2.1 Benthic (Demersal) Species 7.2.2 Bentho-Pelagic Species 7.2.3 Mesopelagic and Bathypelagic Species 7.2.4 Pelagic Species 7.3 Morphological and Physiological Adaptations 7.3.1 Metabolic Adaptations 7.3.2 Freezing Resistance 7.3.3 Blood and Oxygen Transport Systems 7.3.4 Buoyancy Adaptations 7.4 Reproduction andGrowth 7.4.1 Age at Sexual Maturity 7.4.2 Gonad Maturation and Development 7.4.3 Ova Development and Fecundity 7.4.4 Spawning 7.4.5 Hatching Period and Larval Development 7.4.6 Reproductive Strategies 7.5 Age, Growth, Mortality and Biomass Structure 7.5.1 Size and Age 7.5.2 Growth 7.5.3 Mortality 7.5.4 Biomass Estimates 7.6 Feeding Ecology 7.6.1 Feeding Niches and Food Availability 7.6.2 Niche ChangesOver the Life Cycle 7.6.3 Feeding Behavior 7.6.4 Krill Consumption by Antarctic Fish 7.6.5 Feeding Communities 7.7 Factors Controlling the Distribution, Abundance, and Trophic Ecology of Antarctic Fish 7.7.1 Role of Sea Ice 7.7.2 Hydrodynamic Processes 7.7.3 Food Web Dynamics 7.7.4 Life History Processes 185 187 189 190 190 190 191 191 192 192 193 193 193 193 194 195 195 195 196 196 197 197 197198 198 199 199 203 205 207 207 208 208 208

7.1 INTRODUCTION
Investigations into Antarctic fish date back to the midnineteenth century when James Clark Ross's expedition to the Southern Ocean (1839-1843) collected the first fish specimens from Antarctic waters. Early studies were principally taxonomic and Antarctic ichthyology did not begin to broaden to include physiological and ccologicalstudies until the 1950s. In most of the world's seas, fish have been the subject of special study because of their economic

importance. However, the lack of an indigenous population, the harsh climate, and the opportunity to exploit stocks closer to the markets of the world delaycd the exploitation of fish resources of the Southern Occan. As fish stocks declined in other parts of the world'soceans, the possibility of the existence of substantial exploitable stocks in the Southern Ocean attracted the attention of fishing nations. Exploratory fishing commenced in the early 1960s and developed into large-scale fishing around South Georgia in the late 1960s. It has since spread to other parts of the Southern Ocean. 185

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Biology of the Southern Ocean carry out research on fishstocks. During the course of this program, the first attempts were made to estimate the krill consumption of Antarctic coastal fish, together with an evaluation of the role of mesopelagic fish as predators and prey. Simultaneously, or slightly later, several national

Studies of Antarctic fish were boosted by the SCAR/SCOR BIOMASS (Biological Investigation of Southern Ocean Systems and Stocks) thatwas launched in 1976 and ended in 1991. In 1979, a specialized subgroupthe Working Party on Fish Ecology—was established to

(a)

0

10 cm

(e)

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5 cm

(1)

(1)

31cm

FIGURE 7.1 Illustrations of some common Antarctic fish. (a) Champsocephalus gunnari (Fam. Channichthyidae); (b) Channichthys rhinoceratus (Fam. Channichthyidae); (c) Pseudochaenichthys georgianus (Fam.Channichthyidae); (d) Micrornesistius australis (Fam. Gadidae); (e) Krefftichys (Fam. Myctophidae); (f) Dissostichus eleginoides (Fam. Nototheniidae); (g) Notothenia (Notothenia) rossii (Fam. Nototheniidae); (h) Pagothenia bernacchii (Fam. Nototheniidae); (i) Pagothenia magellanica (Fam. Nototheniidae); (j) Pleurogramma antarcticum (Fam. Notothgeniidae). (From FAO, FAO Species Identification Sheets forFishery Purposes, Vol. II, FAO CCAMLR, Rome,

283, 1985. With permission.)

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(e.g., the Offshore Biological Programme (OBP) in the United Kingdom or the Coastal Ecological Programme (ECOKER) in France) and international programs, European Polarstern Study (EPOS), developed investigations into the rclationships bctween fish and other components of thc Southern Ocean ecosystem....
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