Chatham Sound

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Chatham Sound
French: Bassin de Chatham
Looking Northeasterly across Chatham Sound.png
Looking Northeasterly across Chatham Sound
Canada British Columbia relief location map.jpg
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Chatham Sound
Location British Columbia, Canada, between Dundas Islands, Stephens Islands and Tsimpsean Peninsula
Coordinates 54°22′30″N130°35′30″W / 54.37500°N 130.59167°W / 54.37500; -130.59167 [1]
Primary inflows Nass River, Skeena River
Primary outflows Dixon Entrance, Hecate Strait
Max. length70 kilometres (43 mi) [2]
Max. width15–25 kilometres (9.3–15.5 mi) [2]
Surface area1,600 square kilometres (600 mi2)

Chatham Sound is a sound on the North Coast of British Columbia, Canada, bordering on Alaska, United States. It is an ecologically and economically important semi-enclosed basin located between the Dundas and Stephens Islands and the Tsimpsean Peninsula, [1]

Contents

The sound is part of the Inside Passage and extends from Portland Inlet in the north to Porcher Island in the south. [3] It can be divided into two parts, by a line drawn between Tugwell and Melville Islands. [4] The northern part, is influenced by the Nass River outflows and village of Lax Kw'alaams, and the southern part influenced by the Skeena River outflows and the city of Prince Rupert.

It may have been named in 1788 by British Captain Charles Duncan after John Pitt, 2nd Earl of Chatham, who was First Lord of the Admiralty at that time. [1] [3]

Tsimshian have relied on Chatham Sound for millennia, and the continued use and health of its resources remain central to their cultural and economic vitality. [5]

Geography

Chatham Sound is a semi-enclosed basin with an area of about 1,600 square kilometres (600 mi2). It is connected to the open waters of the Hecate Strait and Dixon Entrance via several channels, such as Main, Brown, Hudson Bay, and Edye Passages. Along its southern end, the sound provides access to inland passages such as the Marcus and Arthur Passages, and the Grenville Channel beyond that. [6]

The two major rivers that drain into the sound are the Nass River (via the Portland Inlet) and Skeena River (via the Inverness and Marcus Passages). Because of the large inflow of fresh water the salinity of the sound is lower than the adjacent ocean. [6]

Hydrography

Most of Chatham Sound is less than 100 fathoms (600 ft; 180 m) deep, except in the northern part of the sound where depth exceeds 300 fathoms (1,800 ft; 550 m). [6] Chatham Sound is characterized by lower salinity near-surface waters on its eastern side, transitioning to higher salinity near-surface waters on the western side. [2]

Chatham Sound is an area of very large tides, with tidal ranges reaching peak values of 7.7 metres (25 ft) and an average tidal range of 4.9 metres (16 ft). [7] Currents are proportionately strong, and highly variable due to a combination of large tidal ranges, seasonally strong winds, and large peak freshwater discharges from the Skeena and Nass Rivers. [2]

Surface circulation is dominated by a strongly seasonal freshwater current, which flows into the southeast from three channels: approximately 75% of the Skeena River flows equally through Marcus Passage and Telegraph Passage, while the remaining 25% of the Skeena River flows through Inverness Passage. [8]

Ecology

As a result of tidal mixing, Chatham Sound is an area of particularly high primary productivity and highly concentrated phytoplankton biomass. [9] The sound has the largest diversity of shrimp species in the Pacific North Coast Integrated Management Area, with numbers dominated by humpback shrimp. [9] There are also major aggregations of Dungeness crab in the area. [9]

Once thought to be extinct, sponge reefs are now known to be a significant component of the sound floor. The largest cluster is now designated the Chatham Sound Reef Complex. [10]

The sound is part of the Pacific Flyway migration route, providing important habitats for geese, sea ducks, raptors, and crows. [11]

See also

References

  1. 1 2 3 "Chatham Sound". BC Geographical Names .
  2. 1 2 3 4 Lin Y, Fissel D, Mudge T, Borg K. (2 October 2018). "Baroclinic Effect on Modeling Deep Flow in Brown Passage, BC, Canada". Journal of Marine Science and Engineering. 6 (4): 117. Bibcode:2018JMSE....6..117L. doi: 10.3390/jmse6040117 .{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. 1 2 "Chatham Sound - inlet, British Columbia, Canada". www.britannica.com. Encyclopedia Britannica. Retrieved 25 April 2018.
  4. ↑ "Chart 3989, 3991, Chatham Sound = Northern Part". Sailing Directions, British Columbia Coast, (Northern Portion). II (Ninth Edition): 196. 1983.
  5. ↑ Rabnett, K. (2005). Skeena Basin‑Coastal Planning Linkages (PDF) (Report). Hazelton, British Columbia: Skeena Fisheries Commission. Retrieved 2026-01-11.
  6. 1 2 3 Ronald Wilmot Trites (September 1952). "The Oceanography of Chatham Sound, British Columbia" (PDF). www.oceanecology.ca. University of British Columbia. Retrieved 25 April 2018.
  7. ↑ Lin, Yuehua; Fissel, David (2018-07-06). "The Ocean Circulation of Chatham Sound, British Columbia, Canada: Results From Numerical Modelling Studies Using Historical Datasets". Atmosphere-Ocean. 56 (3): 129–151. Bibcode:2018AtO....56..129L. doi:10.1080/07055900.2018.1473240. S2CID   133663475 . Retrieved 2020-03-09.
  8. ↑ Wang, Li; Pawlowicz, Rich; Ai, Weihua; Covert, Paul (2024). "Wind and river effects on a coastal current in Chatham Sound, British Columbia". Estuarine, Coastal and Shelf Science. 309 108966. doi:10.1016/j.ecss.2024.108966.
  9. 1 2 3 C.L. Clarke; G.S. Jamieson (2006). Identification of Ecologically and Biologically Significant Areas in the Pacific North Coast Integrated Management Area: Phase II – Final Report (PDF) (Report). Fisheries and Oceans Canada. Retrieved 2020-03-22.
  10. ↑ Shaw, J; Conway, K W; Wu, Y; Kung, R (2018). Distribution of hexactinellid sponge reefs in the Chatham Sound region, British Columbia (Report). Geological Survey of Canada, Current Research (Online) 2018-1. doi: 10.4095/306310 . ISBN   978-0-660-24242-2.
  11. ↑ Tera Planning Ltd. and Hay & Co Consultant Inc. (1993). Bulk liquids terminal South Kaien Island, Prince Rupert, BC: Volume II – Environmental Report (PDF) (Environmental report). Prince Rupert, British Columbia, Canada: Prince Rupert Port Corporation. Retrieved 2026-02-03.

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