scholarly journals N ‐Mixture Modeling of River Herring Egg Abundance and Distribution in the Tributaries of the Hudson River

2019 ◽  
Vol 11 (1) ◽  
pp. 48-61
Author(s):  
David M. Kowalik ◽  
William W. Eakin

<em>Abstract.</em>—Pelagic fish abundance and distribution was estimated acoustically at Bowline and Indian Point power plants on the Hudson River, New York, during July, August, and September 1996, in a study designed to determine size-specific spatial and temporal fish abundance and distribution with respect to environmental variables (i.e., photoperiod, depth strata, field). August yielded the greatest (<EM>P </EM>< 0.05) mean density of fish at both power plants. Fish were concentrated in Bowline’s near-field (lagoon) region, thus increasing the potential for deleterious impingement and entrainment effects there. For all size classes, mean fish density was greatest during darkness at both power plants. Generally, the two power plants exhibited similar trends in mean fish abundance with respect to water depth and photoperiod. During July and August mean fish density was significantly higher between 1.5 and 4.5 m (depth strata one) of depth at both power plants. Bowline’s mean fish density was greater under near-field, shallow depth (depth strata one) darkness during July and August. Bowline’s isolated and bathymetrically complex near-field lagoon concentrated pelagic fish compared to the river proper. Hydroacoustics were useful in providing a detailed map of fish distribution relative to each power plant over the course of a few days each month. Hydroacoustic monitoring could mitigate negative effects to pelagic fish at existing and proposed power plants, through sighting of power plant water intake structures or by providing a biological basis for modified production cycles.


<em>Abstract.</em>—Recreational fishing throughout the Hudson River estuary from the federal dam at Troy (river kilometer [rkm] 243) to the George Washington Bridge (rkm 19) was investigated during March 2001 through March 2002. Aerial counting surveys and angler interviews at nearly 200 access points were used to estimate fishing pressure, catch and harvest, catch rates, and various angler attributes. Fishing pressure for the mid-March through November period was estimated at 446,621 angler-hours. Most effort occurred in the late spring by anglers north of the Bear Mountain Bridge (rkm 74). Angling from boats comprised 72.6% of total effort. The total number of fish caught and harvested was estimated at 212,426 and 44,479 individuals, respectively, representing 31 species plus blue crab <em>Callinectes sapidus</em>. Most of the total catch was by boat anglers, although over the entire survey period shore anglers harvested the most fish. In sequence, striped bass <em>Morone saxatilis</em>, river herring <em>Alosa </em>spp., and white perch <em>M. americana </em>were the three most abundant species caught, whereas river herring, white perch, blue crab, and striped bass formed most of the harvest. Catch per unit effort (CPUE) and harvest per unit effort (HPUE) of shore anglers (0.69 fish/h and 0.22 fish/h) were higher than that of boat anglers (0.44 fish/h and 0.02 fish/h). Most anglers throughout spring sought striped bass, whereas during summer and fall boat anglers sought primarily black bass <em>Micropterus </em>spp., with much effort occurring during tournaments. Shore anglers were less focused and sought a broader variety of species. As a group, anglers fishing south of the Bear Mountain Bridge were less aware of fish consumption advisories due to contaminants than anglers fishing elsewhere in the estuary.


2008 ◽  
Vol 58 (11) ◽  
pp. 2133-2142 ◽  
Author(s):  
Nuanchan Singkran ◽  
Mark B. Bain

The spatially explicit abundance exchange model (AEM) was built for four fish species: winter flounder (Pseudopleuronectes americanus), Atlantic silverside (Menidia menidia), eastern silvery minnow (Hybognathus regius), and striped bass (Morone saxatilis) along the Hudson River estuary gradient, New York. The fish and habitat data during 1974–1997 were used to develop and calibrate the AEM; and the fish data during 1998–2001 was used to validate the model. Preference indexes of fish species for dissolved oxygen, salinity, water temperature, and bottom substrates along the gradient were estimated; and these were used to compute habitat preference (HP) of the associated fish species. The species HP was a key variable in the AEM to quantify abundance and distribution patterns of the associated species along the gradient. The AEM could efficiently predict abundance and distribution patterns of all modeled species except striped bass. The model ability for predicting a local distribution range of a fish species with broad tolerance on changing environment like striped bass should be improved.


2007 ◽  
Vol 36 (2) ◽  
pp. 93-104 ◽  
Author(s):  
Wolfgang Lutz ◽  
Niklaus Stulz ◽  
David W. Smart ◽  
Michael J. Lambert

Zusammenfassung. Theoretischer Hintergrund: Im Rahmen einer patientenorientierten Psychotherapieforschung werden Patientenausgangsmerkmale und Veränderungsmuster in einer frühen Therapiephase genutzt, um Behandlungsergebnisse und Behandlungsdauer vorherzusagen. Fragestellung: Lassen sich in frühen Therapiephasen verschiedene Muster der Veränderung (Verlaufscluster) identifizieren und durch Patientencharakteristika vorhersagen? Erlauben diese Verlaufscluster eine Vorhersage bezüglich Therapieergebnis und -dauer? Methode: Anhand des Growth Mixture Modeling Ansatzes wurden in einer Stichprobe von N = 2206 ambulanten Patienten einer US-amerikanischen Psychotherapieambulanz verschiedene latente Klassen des frühen Therapieverlaufs ermittelt und unter Berücksichtigung unterschiedlicher Patientenausgangscharakteristika als Prädiktoren der frühen Veränderungen mit dem Therapieergebnis und der Therapiedauer in Beziehung gesetzt. Ergebnisse: Für leicht, mittelschwer und schwer beeinträchtigte Patienten konnten je vier unterschiedliche Verlaufscluster mit jeweils spezifischen Prädiktoren identifiziert werden. Die Identifikation der frühen Verlaufsmuster ermöglichte weiterhin eine spezifische Vorhersage für die unterschiedlichen Verlaufscluster bezüglich des Therapieergebnisses und der Therapiedauer. Schlussfolgerungen: Frühe Psychotherapieverlaufsmuster können einen Beitrag zu einer frühzeitigen Identifikation günstiger sowie ungünstiger Therapieverläufe leisten.


Ecography ◽  
2000 ◽  
Vol 23 (1) ◽  
pp. 50-59 ◽  
Author(s):  
Ian G. Henderson ◽  
Juliet A. Vickery ◽  
Robert J. Fuller

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