We compared a process‐based invertebrate drift and drift‐feeding net rate of energy intake (NREI) model and a traditional hydraulic‐habitat model (using the RHYHABSIM [River Hydraulics and Habitat Simulation] software program) for predicting the flow requirements of 52‐cm Brown Trout Salmo trutta in a New Zealand river. Brown Trout abundance predicted by the NREI model for the constant drift concentration–flow scenarios were asymptotic or linear, depending on drift concentration, increasing through the mean annual low flow (MALF; 17 m3/s). However, drift concentration increased with flow, consistent with passive entrainment. The predicted fish abundance–flow relationship based on flow‐varying drift concentration increased logistically, and more steeply, with flow through the MALF and beyond. Predictions for the relationship between weighted useable area (WUA) and flow were made for three sets of drift‐feeding habitat suitability criteria (HSC) developed on three midsized and one large New Zealand river (flow at sampling was 2.8–4.6 m3/s and ~100 m3/s, respectively) and the South Platte River, Colorado (flow at sampling, 7–18 m3/s). The midsized‐river HSC ascribe lower suitability to water velocities > 0.6 m/s. They predicted WUA peaking at 10–11 m3/s, well below the MALF. The WUA–flow relationships for the two large‐river HSC were asymptotic at about 22 m3/s. Overall, WUA appears to underestimate the flow needs of drift‐feeding salmonids. The NREI model showed that assessing flow needs of drift‐feeding fish is more complex than interpreting a WUA–flow relationship based only on physical habitat suitability. The relationship between predicted fish abundance and flow is an emergent property of flow‐dependent drift‐foraging dynamics interacting with flow‐dependent drift concentration and drift flux, local depletion of drift by feeding fish, and flow‐related replenishment of drift from the bed and dispersion. It is time that the principles and predictions of drift–NREI models influence assessments of habitat capacity and instream flow needs of drift‐feeding fish. Received April 10, 2015; accepted November 10, 2015 Published online April 27, 2016

The Kakeror~ or Rarotonga Flycatcher (Pomarea dimidiata ), is an endangered monarch flycatcher endemic to the island of Rarotongag Cook Islands. This bird was reported to be common until the middle of the nineteenth century, but it declined before 1885 and was thought to be extinct early this century. A small population persisted in the rugged interior of Rarotonga; in 1987 the population stood at 38 birds but was in decline. We determined that introduced predatorg especially ship rats (Rattus rattus), were affecting breeding succes~ Through a program of experimental man-agemen~ aimed mainly at rodent control the population increased from a low of 29 birds in Spring 1989 to 60 birds in Spring 1993. The recovery can be attributed to both improved breeding success and increased adult survivorship.

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Abstract.-Management of the effects of water quality and flow on fisheries requires an understanding of the factors that control fish movements. We used radiotelemetry to monitor the movements of adult brown trout Salmo trutta in a New Zealand river over 11 months (September 2004 to August 2006 and linked those movements to the changes in flow and water temperature. Individual fish moved up to 41 km during the study. However, most fish moved less than 1 km. All of the trout that showed little movement throughout the summer were living in relatively deep pools that presumably provided cover. The rates of movement declined steadily over the spring-summer period, as flow decreased and water temperature increased. The percentage of fish moving was positively related to the average daily flow during the interval between tracking occasions and negatively related to the average daily water temperature, less than 20% of the tagged fish moving once temperatures were above 198C. A severe, 50-year flood occurred in March 2005 and was associated with the mortality of 60-70% of the remaining tagged fish, confirming that flood-induced mortality can affect a substantial proportion of an adult brown trout population.Research on river-resident salmonids over the last 15 years has indicated that widespread movement is much more common than previously thought (Gowan et al.

The effects of natural flow variation on juvenile brown trout population dynamics were investigated by biannual sampling over 5.5 years in the Rainy River, a tributary of the Motueka River. A large flood in late March (50-year return period) substantially reduced the density (by 66%) and biomass (by 73%) of 0' trout over autumnÁspring, but the cohort responded with compensatory survival to achieve similar density and biomass by spring as in other years. A lowflow event in FebruaryÁApril (return period !8.4 years), when 7-day low flows fell to 56% of the 7-day mean annual low flow (MALF) and were less than the MALF for 46 days, had no adverse affect on the population. We found no evidence for density-dependent growth. However, there was strong evidence for a two-phase self-thinning response in density, with no self-thinning occurring over summer (i.e. the 0' population remained below carrying capacity) until a threshold mass of 22.08 g (length 0 123.7 mm) was attained in autumn after which severe selfthinning took place over autumn to spring. The results indicate that over springÁautumn the population is insensitive to flow reduction and that over autumnÁspring the effects of high (and probably low) flow events on local abundance and biomass are offset by compensatory (densitydependent) survival. However, effects on the contribution of migrants to the downstream population remain unknown. The study identified ecological redundancy, which could be exploited for flow allocation. Significantly, it has shown that minimum flows equivalent to the MALF (often advocated by New Zealand conservation and fisheries management organisations) are not always necessary for sustaining juvenile trout populations.