John Piatt, Ph.D. (Former Employee)

We evaluated pigeon guillemots (Cepphus columba) as monitors of nearshore fish abundance and community composition during 1995-1999 at Kachemak Bay, Alaska. We studied the composition of chick diets at 10 colonies and simultaneously measured fish abundance around colonies with beach seines and bottom trawls. Sandeels (Ammodytes hexapterus) formed the majority of the diet at one group of...

Fish were sampled with beach seines and small-meshed beam trawls in nearshore ( 1 km) and shallow ( 25 m) habitats on the southern coast of Kachemak Bay, Cook Inlet, Alaska, from June to August, 1996-1998. Fish distributions among habitats were analysed for species composition, catch-per-unit-effort (CPUE) and frequency of occurrence. Two oceanographically distinct areas of Kachemak Bay...

Mechanisms of population differentiation in highly vagile species such as seabirds are poorly understood. Previous studies of marbled murrelets (Brachyramphus marmoratus; Charadriiformes: Alcidae) found significant population genetic structure, but could not determine whether this structure is due to historical vicariance (e.g., due to Pleistocene glaciers), isolation by distance, drift...

We have been conducting detailed studies of the biology of seabirds in relation to oceanography and forage fish ecology in lower Cook Inlet, Alaska, since 1995. This fortuitously allowed us to document biological effects of the 1997/98 ENSO in this region. Anomalously warm sea surface temperatures (SSTs) were observed in the Gulf of Alaska (GOA) beginning in June of 1997, but not in Cook...

Late summer counts of juveniles at sea are used as an index of Marbled Murrelet (Brachyramphus marmoratus) reproductive success, but little is known about juvenile dispersal or habitat use. Further, it is not known whether these counts accurately reflect absolute breeding success. To address these questions we conducted five boat surveys for Marbled Murrelets and Pigeon Guillemots...

In the course of directed research on glaucous-winged gulls, we investigated the numbers and activities of all breeding and non-breeding seabirds associated with South Marble Island in Glacier Bay, Alaska, during mid-May to late July, 1999. Most observations were made from the island; additional observations were made during transportation to and from the island. Data were collected on...

Six species of sand lance (Ammodytes) in temperate and boreal regions are currently recognized. Sand lance can occupy a wide range of environmental conditions, but all appear to be dormant predominantly in winter, and one species is in summer also. They lack a swim bladder and spend much of their time buried in specific substrates. Copepods are the primary food. Spawning usually occurs...

Although much taxonomic confusion exists within the genus Ammodytes, six species are currently recognized: personatus, hexapterus, americanus, dubius, tobianus, and marinus. Sand lance are both euryhaline and eurythermal, as well as tolerant of reduced oxygen concentrations. The absence of a swim bladder allows this narrow, elongate fish to spend much time buried dormant in intertidal...

Sand lance (Ammodytes) constitute a major prey for at least some populations of over 100 species of consumer, including 40 species of birds, 12 species of marine mammals, 45 species of fishes, and some invertebrates. Variation in the availability of sand lance (and other forage fishes) can have major effects on the breeding success and survival of their predators. Commercial fishing and...

Seabirds are prominent and highly visible components of marine ecosystems that will be affected by global climate change. The Bering Sea region is particularly important to seabirds; populations there are larger and more diverse than in any similar region in North America—over 90% of seabirds breeding in the continental United States are found in this region. Seabirds, so named because...

Pacific sand lance Ammodytes hexapterus in Kachemak Bay, Alaska, showed no sexual dimorphism in length-to-weight (gonad-free) ratio or length-at-age relationship. Most matured in their second year, males earlier in the season than females, but females (31%) attained a higher gonadosomatic index than males (21%). Sand lance spawned intertidally once each year in late September and October...

On 13 June 1993, a new Kittlitz's murrelet (Brachyramphus brevirostris) nest was discovered near Red Mountain on the Kenai Peninsula, Alaska. The nest was on a 22° slope at about 900 m elevation with a northeast aspect, and contained a 60.2 × 40.6 mm egg that weighed 49.0 g. Downy feathers and weathered fecal material found at the nest indicated re-use from a previous year, suggesting...