Humpback Whales in Glacier Bay National Monument, Alaska Part 1

Humpback Whales in Glacier Bay National Monument, Alaska.

by United States Department of Commerce, Marine Mammal Commission.

PREFACE

In 1976, the National Park Service initiated a study to determine whether increased boat traffic or boating activities were having an adverse impact on humpback whales inhabiting Glacier Bay National Monument during the summer months. In 1978, the whales entered the Bay as usual, but left sooner than expected. The scientists conducting the whale studies believed that the early departure of the whales was precipitated by increased boat traffic in the Bay and, in 1979, the Park Service, in consultation with the cruise s.h.i.+p industry, developed and implemented operational guidelines for vessel course and speed in designated areas, where it was felt that vessel interactions with incoming whales could cause the most disturbance.

Researchers spent many hours looking for whales in the Bay during the early part of the 1979 summer season, but few whales were seen.

Several interactions between vessels and those whales present in the Bay were observed and, on one occasion, a whale known to have had an interaction with a vessel left the Bay. Monument personnel discussed the problem with the area office of the National Park Service. A number of options, including emergency closure of the Bay were considered. It was decided to provide funds for a more thorough a.n.a.lysis of the available information on whale/vessel interactions, and to consult with the National Marine Fisheries Service pursuant to Section 7 of the Endangered Species Act.

The NMFS was advised of the situation and, on 10 August 1979, NPS and NMFS representatives met in Seattle, Was.h.i.+ngton to review available information concerning the nature and possible causes of the departure of whales from the Bay. Another meeting was held in late August to discuss the problem with members of the cruise s.h.i.+p industry. It was agreed that additional research was needed to better define the nature and possible causes of the problem and that a meeting should be held to discuss possible research approaches with other professionals in the marine mammal field. These decisions led to the meeting described in this report.

Subsequent to the meeting reported here, the National Marine Fisheries Service in a letter dated December 3, 1979, responded to the National Park Service's request for a Section 7 consultation. A copy of the NMFS's response is provided in Appendix D of this report.

INTRODUCTION

Humpback whales (_Megaptera novaeangliae_) inhabit the inland waters of southeast Alaska, including Glacier Bay during the summer months (June-August). In the years from 1967 through 1977, 20 to 25 individually recognizable whales were observed feeding in Glacier Bay.

In 1978, the whales entered the bay but left earlier than expected. In 1979, only a few humpbacks entered Glacier Bay. The limited information available suggests that increased human activity in the Bay may have been responsible, at least in part, for the observed s.h.i.+ft in distribution. Increased human use of coastal waters is not limited to Glacier Bay and the movement of humpbacks from Glacier Bay to areas outside the Bay may be symptomatic of a larger problem.

The purposes of this meeting were: (1) to review available information concerning the nature and possible causes of the movement of whales from Glacier Bay; (2) to review present and planned research and management actions relating to humpback whales in Glacier Bay and southeast Alaska; and (3) to identify additional research or management actions that may be necessary to conserve and protect the North Pacific population(s) of humpback whales.

The meeting was held on the 12th and 13th of October 1979, at the College of Fisheries, University of Was.h.i.+ngton, Seattle. The meeting agenda is included as Appendix A. Individuals who made formal presentations at the meeting are identified on the agenda. A list of the meeting attendees, their organizations, addresses, and telephone numbers are listed in Appendix B.

BACKGROUND

=Distribution and Abundance of Humpback Whales in the North Pacific=[1]

Humpback whales are seasonal migrants found in all of the world's oceans. In the North Pacific, humpback whales winter in tropical regions over the shallow coastal shelfs a.s.sociated with the Hawaiian Islands, Baja California, central Mexico, the Ryukyu Islands, Bonin Islands, and Mariana Islands. They summer in cold temperate regions, also over shallow coastal shelfs, from Point Conception, California, north through Alaska, west through the Aleutians, and south to Honshu Island, j.a.pan. Calving and probably breeding occur on the wintering grounds. Feeding is believed to occur primarily in the summering grounds.

In Alaska, humpback whales are known to inhabit Prince William Sound, the waters of the Alexander Archipelago, and the waters adjacent to Kodiak Island and the Aleutians. Some whales may also overwinter in the northern summering areas.

The distribution, movements, abundance, and habitat requirements of humpback whales are not well known. Based upon j.a.panese catch statistics, the pre-exploitation population of humpback whales in the North Pacific is estimated to have been approximately 15,000. Much of the exploitation of humpback whales occurred in the twentieth century, especially during the early 1960's. A small number of whaling stations established in southeast Alaska took humpbacks between 1907 and 1922.

In 1966, the International Whaling Commission imposed a worldwide ban on the taking of humpback whales.

The present population of humpback whales in the North Pacific is estimated to be about 1,000 animals. The number occurring in tropical waters during the winter is thought to be about 600-700 in Hawaii, 200-300 in Mexican waters, and a "few whales" in the western North Pacific. More than 100 individual whales have been identified in the inland waters of southeast Alaska during the summer. Tagging experiments with Discovery Marks indicate movement between the Aleutian Islands and the Western North Pacific; recent photo-identification studies have shown movement from Southeast Alaska to both the Hawaiian Islands and Baja (and southern coastal) Mexico.

There is no substantive evidence to indicate whether the number of humpback whales, on either summer or winter grounds, in the North Pacific is increasing or decreasing.

[Footnote 1: This summary is based on information provided at the meeting by Drs. Michael Tillman and Louis Herman.]

[Ill.u.s.tration: FIGURE 1. (from Jurasz and Jurasz, 1979)]

Map showing location of Glacier Bay, Lynn Ca.n.a.l and Fredrick Hole in Southeast Alaska Alexander Archipelago

[Ill.u.s.tration: FIGURE 2. NOS Chart 17300]

Soundings in Fathoms Scale 1:209,978

[Ill.u.s.tration: Figure 3. GLACIER BAY, ALASKA]

SHOWING FORMER POSITIONS OF TERMINI 1760-1966 (from Hale and Wright, 1979)

=Glacier Bay=[2]

Glacier Bay is located near the north end of the Alexander Archipelago (Figures 1 and 2). The Bay opens into Cross Sound and Icy Strait of the Inside Pa.s.sage of southeast Alaska. When Vancouver discovered the area in 1780, glacial ice filled the Bay to its mouth (Figure 3). In 1891, when the Bay was first mapped, Muir Inlet was still filled with ice. Today the ice has retreated up the right (Muir Inlet) arm of the "Y" shaped Bay to tide-water levels. Recently, glacial ice has started to readvance in the upper reaches of the west inlets of the Bay.

The Bay is defined by shallow sills at its entrance and the entrance to Muir Inlet. Constricted channels in which tidal currents are locally strong occur between sediment covered sh.o.r.es in the lower end of the Bay and the east (Muir) inlet. Deep, unconstricted bedrock channels and basins with weak currents occur in mid-Bay and the west inlet. These features and the configuration of the bay produce a tidal range of 8 meters. There is reduced mixing of waters within the Bay and between the Bay and Cross Sound/Icy Strait. Annual precipitation up to 4 meters, coupled with glacial melt water, create a surface layer and flow of cold fresh water out of the Bay. Strong flood tides push sea water into the Bay over the sills. The dynamics of the flow may effect the behavior and timing of the movement of whales into (on flood tides) and out of (on ebb tides) the Bay (see below).

During the winter, an increase in sea water flow and mixing occur.

Increased nutrient levels and sunlight in spring/summer provide sufficient nutrients and energy for phytoplankton "blooms" to occur.

In turn, zooplankters appear, especially in the open areas of mid and lower Bay (e.g., euphausiids) and along glacial ice faces (e.g., mysids and amphipods). By autumn, plankton concentrations diminish as light and nutrient levels decrease. Small schooling fish, (e.g., capelin, _Mallotus villosus_ and Pacific sand lance, _Ammodytes hexapterus_), feed on the plankton when it becomes available. Both fish and plankton are consumed by humpback whales as well as by other predators. Other marine mammal species reported in the Bay are harbor seals (_Phoca vitulina_), harbor porpoise (_Phocoena phocoena_), killer whales (_Orcinus orca_), and minke whales (_Balaenoptera acutorostrata_).

[Footnote 2: This summary is based on information provided at the meeting by Mr. Gregory Streveler.]

=Humpback Whales in Glacier Bay=[3]

The distribution in and use of Glacier Bay by humpback whales was not well known until Charles and Virginia Jurasz began observations in 1973. Prior to this, only personal recollections of Park Service employees of the occurrence of humpback whales in the 1950's and the 1960's exist. In 1967, 60 identifiable humpback whales were observed in three southeast Alaskan areas, i.e., Lynn Ca.n.a.l, Frederick Sound, and Glacier Bay. The number of identifiable whales remained relatively constant until 1974 in Lynn Ca.n.a.l, and 1978 (July 17) in Glacier Bay (Tables 1-3). In the respective areas, the number of identified whales decreased from 15 and 19 to 1 and 3, respectively. Concurrently, the number of identified whales sighted in Frederick Sound increased.

TABLE 1. Relative abundance and distribution of identified humpback whales in southeast Alaskan waters 1967-79[a]

Year 67 68 69 70 71 72 73 74 75 76 77 78 79 -------------------------------------------------------------------

Glacier Bay 20 20 20 20 20 20 25 25 25 25 25 19/3[b] 3 -------------------------------------------------------------------

Lynn Ca.n.a.l 15 15 15 15 15 15 15 1 3 3 3 1/5 5 -------------------------------------------------------------------

Frederick 25 25 25 25 25 25 25 35 40 40 40 40/50 80 Sound -------------------------------------------------------------------

Total 60 60 60 60 60 60 65 61 68 68 68 60/58 88 -------------------------------------------------------------------

[Footnote a: Specific dates of censuses, sighting techniques and sighting effort not given. Based on a table presented by the Juraszs at the meeting.]

[Footnote b: First number signifies number originally counted at beginning of season/second number after decrease in number of whales in Glacier Bay and increase in other areas. The identified whales that left Glacier Bay are not necessarily the same individuals that produced the increased numbers in Lynn Ca.n.a.l and Frederick Sound later.]