Are Fishes Attracted to Piers? Movements and Association of Marine Fishes to a Public Fishing Pier within a Commercial Harbor

Ocean fishing piers are ubiquitous along the world’s coastline, yet little research has examined how these structures can attract and retain fishes. Fishers routinely use these manmade structures as a reliable way to catch fish for subsistence or recreation. California halibut (Paralichthys californicus) and white croaker (Genyonemus lineatus) are commonly caught from fishing piers in southern California; however, some individuals have been found to contain high concentrations of hazardous contaminants. Thus, human health hazard warnings are posted throughout the Los Angeles area to limit fish consumption. To document attraction, residency, and association to fishing piers, forty-two California halibut and 198 white croaker were tagged with acoustic transmitters in regions of the Los Angeles and Long Beach Harbors, including a local fishing pier, and the movements of these fish were tracked throughout a 1.5 year period. Average (± SD) fish residency near piers was 90.5 ± 104.8 days for California halibut and 31.9 ± 25.7 days for white croaker. Only 18% of white croaker and 6% California halibut were detected migrating to the pier from other locations of the LA-LB Harbors, and most spent \u3c 10 min within 300 m of the public fish pier. Only 14% of California halibut and 0.35% of white croaker geo-positions were within casting range (approximately 30 m) of the pier, thus California halibut show the greatest potential affinity for pier habitat. Due to their movement patterns and habitat associations California halibut are much more likely to be attracted to fishing piers than white croaker

Fishing pier association and movements of white croaker and California halibut within the Los Angeles and Long Beach Harbors

California halibut and white croaker are commonly caught from fishing piers; however, some individuals have been found to contain high amounts of hazardous contaminants. As a result, human health hazard warnings are posted throughout the Los Angeles area. To document attraction, residency, and association to fishing piers, the movements of 42 California halibut and 198 white croaker were tracked within the Los Angeles and Long Beach Harbors for 1.5 years. Fish residency near piers was 90.5 ± 104.8 days for California halibut and 31. 9 ± 25.7 days for white croaker. Only 18% of white croaker and 6% California halibut were detected migrating to the pier, and most spent < 10 min within 300 m of the pier. Only 14% of California halibut and 0.35% of white croaker positions were within casting range (approximately 30 m) of the pier, thus California halibut show the greatest potential affinity for pier habitat

L'influenza del DTM per la valutazione del rischio di scivolamento della coltre superficiale nei bacini montani

Nell\u2019ambito dello studio dei fenomeni geologico-ambientali connessi al rischio idrogeologico, \ue8 frequente il ricorso a modelli di calcolo numerico che traggono l\u2019informazione relativa all\u2019altimetria dai Modelli Digitali del Terreno (DTM) di origine aerofotogrammetrica. Lo sviluppo della tecnologia LiDAR (Light Detection And Ranging) offre la possibilit\ue0 di analizzare la precisione dei DTM derivati dalla cartografia a grande scala, in particolar modo nelle aree montane in cui, per la presenza di densa vegetazione, la corretta restituzione morfologica del terreno \ue8 parzialmente ostacolata. Nella verifica sperimentale sono stati confrontati i DTM ricavati dalla CTRN in scala 1:5000 del Friuli Venezia Giulia ed i corrispondenti DTM ottenuti dall\u2019elaborazione di scansioni laser (LiDAR) aeree. I risultati consentono di verificare come il notevole miglioramento nella descrizione della morfologia del terreno apportata dalla tecnica LiDAR si manifesti, a livello locale, in sostanziali differenze nella misura delle altezze espresse dai DTM e, conseguentemente, nella definizione delle aree a rischio d\u2019instabilit\ue0

REALIZZAZIONE E CONFRONTO DI MODELLI DIGITALI DEL TERRENO

none4noneA. BARILOTTI; A.BEINAT; Guido PREARO; F.SEPICA., Barilotti; A., Beinat; Prearo, Guido; F., Sepi