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We report the design, operation and preliminary results obtained using a portable, bottomless, "popnet" in dense stands of submersed aquatic vegetation (SAV). Effort and time for on-site assembly and operation are minimal as are construction costs. Fish density and biomass values derived from use of pop-net are far greater than those obtained from either haul seining or electrofishing in the same bed. The pop-net design a pears especially useful for revealing spatial and temporal patterns of small fish distribution within dif;erent SAV species. Zusammenfassung Quantitative Probenentnahme von Kleinfischen in dichten Vegetationen: Konstruktion und Felderprobung eines tragbaren ,Pop"-NetzesWir berichten uber die Konstruktion, den Betrieb und die vorlaufigen Ergebnisse eines tragbaren ,Pop"-Netzes ohne Boden in dichten Ansammlungen von Unterwasserve etation (SAV). Aufwand und Zeit fur den Zusammenbau an On und Stelle sowie die Herstellungs~osten sind minimal. Die Werte fiir Fischdichte und Biomasse, die mit Pop-Netzen erzielt werden, sind vie1 groBer als die mit senkrechten Schleppneuen oder Elektrofischen im selben Bett erhaltenen Daren. Die Pop-Netzkonstruktion scheint besonders geeignet fiir die Untersuchung der raumlichen und zeitlichen Erscheinungsformen der Kleinfischverteilung innerhalb verschiedener Arten von Unterwasservegetation (SAV). Rt5sumt5 Prise quantitative d'kchantillons de petits poissons en vkgktation dense: construction et exphimentation de "pop-nets" @ets)pottntifsDans cet article il est uestion de la construction, de l'utilisation et des risultats priliminaires obtenus grke au *pop-nern, ;let portatif et sans fond, dans une vigitation aquatique dense et submergie. Efforts et temps pour assembler sur lace ainsi qu'utiliser ce *pop-netx sont minimes, comme le sont les frais de construction. La densiti de population de etits poissons et la valeur de la biomasse obtenues avec le epo netu sont plus importantes que celles ogtenues i la p%he tlectro ou i la piche au coup de filet faites Bins le meme ilkment (banc de poissons). Le modile wpop-net. parait &re specialement utile pour dicouvrir les distributions temporelles et spatiales de petits poissons dans diffirentes vigitations aquatiques denses et submergies.

Challenge studies with Mycobacterium marinum clearly demonstrate that a poor diet affects the progression and severity of mycobacteriosis in striped bass Morone saxatilis. Fish (n = 512 total, wt = 65 ± 15 g) were inoculated intraperitoneally with 10 4 colony-forming units (CFU) g -1 body weigth (BW) or a physiological saline solution (controls) and evaluated for 8 mo. Inoculated fish fed a low-ration diet (0.15% BW d -1 ) developed a severe, systemic infection characterized by a high bacterial load (>10 8 CFU g -1 spleen) and poor granuloma formation, which commonly progressed to mortality by 6 wk. In contrast, inoculated fish fed an adequate ration diet (1% BW d -1 ) developed classic granulomatous inflammation of reduced severity and total body energy similar to that found in uninoculated controls (p > 0.05). After 4 wk, fish fed adequate rations maintained an equilibrium state throughout the study period, even though 10 6 CFU g -1 spleen mycobacteria were consistently cultured. In a second study, reactivation of an acute inflammatory state was demonstrated by placing previously infected fish on reducing diets (0.073% BW d -1). In both studies, the energetic demand of this disease was only appreciable when associated with active, severe, inflammatory states. To our knowledge, this study is the first to demonstrate the interaction of diet and mycobacteriosis in fish.

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